GLYCINE

Glycine is an amino acid that has a single hydrogen atom as its side chain.
Glycine is the simplest stable amino acid (carbamic acid is unstable), with the chemical formula NH2‐CH2‐COOH.
Glycine is one of the proteinogenic amino acids.

IUPAC Name: Aminoacetic acid
CAS Number: 56-40-6
EC Number: 200-272-2
Chemical Formula: C2H5NO2

Other names: 2-Aminoacetic acid, 56-40-6, aminoacetic acid, Glycocoll, Aminoethanoic acid, Glycolixir, H-Gly-OH, Glycosthene, Glicoamin, Aciport, Padil, Hampshire glycine, L-Glycine, Amitone, Leimzucker, Aminoazijnzuur, Acetic acid, amino-, Glycinum, Gyn-hydralin, FEMA No. 3287, Acido aminoacetico, Acide aminoacetique, Acidum aminoaceticum, gly, Glykokoll, Aminoessigsaeure, Hgly, CCRIS 5915, HSDB 495, AI3-04085, NSC 25936, 25718-94-9, H2N-CH2-COOH, amino-Acetic acid, EINECS 200-272-2, UNII-TE7660XO1C, MFCD00008131, NSC-25936, [14C]glycine, TE7660XO1C, DTXSID9020667, CHEBI:15428, NSC25936, CHEMBL773, DTXCID90667, EC 200-272-2, aminoacetate, Athenon, NCGC00024503-01, CAS-56-40-6, Aminoessigsaure, Aminoethanoate, 18875-39-3, amino-Acetate, 2-aminoacetate, Glycine;, [3H]glycine, H-Gly, L-Gly, Gly-CO, Gly-OH, L-Glycine,(S), [14C]-glycine, Corilin, Tocris-0219, NH2CH2COOH, Biomol-NT_000195, bmse000089, bmse000977, WLN: Z1VQ, Gly-253, GTPL727, AB-131/40217813, BPBio1_001222, GTPL4084, GTPL4635, BDBM18133, AZD4282, Glycine, 98.5-101.5%, Pharmakon1600-01300021, Glycine 1000 microg/mL in Water, 2-Aminoacetic acid;Aminoacetic acid, BCP25965, CS-B1641, HY-Y0966, Tox21_113575, HB0299, NSC760120, s4821, STL194276, AKOS000119626, Tox21_113575_1, AM81781, CCG-266010, DB00145, NSC-760120, NCGC00024503-02, NCGC00024503-03, BP-31024, FT-0600491, FT-0669038, G0099, G0317, EN300-19731, A20662, C00037, D00011, D70890, M03001, L001246, Q620730, SR-01000597729, Q-201300, SR-01000597729-1, Q27115084, B72BA06C-60E9-4A83-A24A-A2D7F465BB65, F2191-0197, Z955123660, InChI=1/C2H5NO2/c3-1-2(4)5/h1,3H2,(H,4,5

Glycine is encoded by all the codons starting with GG (GGU, GGC, GGA, GGG). Glycine is integral to the formation of alpha-helices in secondary protein structure due to the "flexibility" caused by such a small R group.
Glycine is also an inhibitory neurotransmitter interference with its release within the spinal cord (such as during a Clostridium tetani infection) can cause spastic paralysis due to uninhibited muscle contraction.

Glycine is the only achiral proteinogenic amino acid.
Glycine can fit into hydrophilic or hydrophobic environments, due to its minimal side chain of only one hydrogen atom.

Glycine was discovered in 1820 by French chemist Henri Braconnot when he hydrolyzed gelatin by boiling it with sulfuric acid.
He originally called it "sugar of gelatin", but French chemist Jean-Baptiste Boussingault showed in 1838 that it contained nitrogen.

In 1847 American scientist Eben Norton Horsford, then a student of the German chemist Justus von Liebig, proposed the name "glycocoll"; however, the Swedish chemist Berzelius suggested the simpler current name a year later.
The name comes from the Greek word γλυκύς "sweet tasting" (which is also related to the prefixes glyco- and gluco-, as in glycoprotein and glucose).
In 1858, the French chemist Auguste Cahours determined that glycine was an amine of acetic acid.

Glycine's acid base properties are most important.
In aqueous solution, glycine is amphoteric: below pH = 2.4, it converts to the ammonium cation called glycinium.
Above about 9.6, it converts to glycinate.

Glycine functions as a bidentate ligand for many metal ions, forming amino acid complexes.
A typical complex is Cu(glycinate)2, i.e. Cu(H2NCH2CO2)2, which exists both in cis and trans isomers.

With acid chlorides, glycine converts to the amidocarboxylic acid, such as hippuric acid and acetylglycine.
With nitrous acid, one obtains glycolic acid (van Slyke determination).
With methyl iodide, the amine becomes quaternized to give trimethylglycine, a natural product:

Glycine condenses with itself to give peptides, beginning with the formation of glycylglycine:

Pyrolysis of glycine or glycylglycine gives 2,5-diketopiperazine, the cyclic diamide.

Glycine forms esters with alcohols.
They are often isolated as their hydrochloride, e.g., glycine methyl ester hydrochloride.
Otherwise the free ester tends to convert to diketopiperazine.

As a bifunctional molecule, glycine reacts with many reagents.
These can be classified into N-centered and carboxylate-center reactions.

Biosynthesis of Glycine:
Glycine is not essential to the human diet, as it is biosynthesized in the body from the amino acid serine, which is in turn derived from 3-phosphoglycerate, but one publication made by supplements sellers seems to show that the metabolic capacity for glycine biosynthesis does not satisfy the need for collagen synthesis.
In most organisms, the enzyme serine hydroxymethyltransferase catalyses this transformation via the cofactor pyridoxal phosphate:
serine + tetrahydrofolate → glycine + N5,N10-methylene tetrahydrofolate + H2O

In E. coli, glycine is sensitive to antibiotics that target folate.

In the liver of vertebrates, glycine synthesis is catalyzed by glycine synthase (also called glycine cleavage enzyme).
This conversion is readily reversible.

In addition to being synthesized from serine, glycine can also be derived from threonine, choline or hydroxyproline via inter-organ metabolism of the liver and kidneys.

Degradation of Glycine:
Glycine is degraded via three pathways.
The predominant pathway in animals and plants is the reverse of the glycine synthase pathway mentioned above.
In this context, the enzyme system involved is usually called the glycine cleavage system:

In the second pathway, glycine is degraded in two steps.
The first step is the reverse of glycine biosynthesis from serine with serine hydroxymethyl transferase.
Serine is then converted to pyruvate by serine dehydratase.

In the third pathway of its degradation, glycine is converted to glyoxylate by D-amino acid oxidase. Glyoxylate is then oxidized by hepatic lactate dehydrogenase to oxalate in an NAD+-dependent reaction.

The half-life of glycine and its elimination from the body varies significantly based on dose.
In one study, the half-life varied between 0.5 and 4.0 hours.

Physiological function of Glycine:
The principal function of glycine is it acts as a precursor to proteins. Most proteins incorporate only small quantities of glycine, a notable exception being collagen, which contains about 35% glycine due to its periodically repeated role in the formation of collagen's helix structure in conjunction with hydroxyproline.[27][31] In the genetic code, glycine is coded by all codons starting with GG, namely GGU, GGC, GGA and GGG.

As a biosynthetic intermediate
In higher eukaryotes, δ-aminolevulinic acid, the key precursor to porphyrins, is biosynthesized from glycine and succinyl-CoA by the enzyme ALA synthase.
Glycine provides the central C2N subunit of all purines.

As a neurotransmitter
Glycine is an inhibitory neurotransmitter in the central nervous system, especially in the spinal cord, brainstem, and retina.
When glycine receptors are activated, chloride enters the neuron via ionotropic receptors, causing an inhibitory postsynaptic potential.
Strychnine is a strong antagonist at ionotropic glycine receptors, whereas bicuculline is a weak one.

Glycine is a required co-agonist along with glutamate for NMDA receptors.
In contrast to the inhibitory role of glycine in the spinal cord, this behaviour is facilitated at the (NMDA) glutamatergic receptors which are excitatory.
The LD50 of glycine is 7930 mg/kg in rats (oral), and it usually causes death by hyperexcitability.

Uses of Glycine:
In the US, glycine is typically sold in two grades: United States Pharmacopeia, and technical grade.
USP grade sales account for approximately 80 to 85 percent of the U.S. market for glycine.
If purity greater than the USP standard is needed, for example for intravenous injections, a more expensive pharmaceutical grade glycine can be used.
Technical grade glycine, which may or may not meet USP grade standards, is sold at a lower price for use in industrial applications, e.g., as an agent in metal complexing and finishing.

Animal and human foods
Glycine is not widely used in foods for its nutritional value, except in infusions.
Instead, glycine's role in food chemistry is as a flavorant.
Glycine is mildly sweet, and it counters the aftertaste of saccharine.
Glycine also has preservative properties, perhaps owing to its complexation to metal ions.
Metal glycinate complexes, e.g. copper(II) glycinate are used as supplements for animal feeds.

The U.S. "Food and Drug Administration no longer regards glycine and its salts as generally recognized as safe for use in human food".

Chemical feedstock
Glycine is an intermediate in the synthesis of a variety of chemical products.
Glycine is used in the manufacture of the herbicides glyphosate, iprodione, glyphosine, imiprothrin, and eglinazine.
Glycine is used as an intermediate of the medicine such as thiamphenicol.[citation needed]

Laboratory research
Glycine is a significant component of some solutions used in the SDS-PAGE method of protein analysis. Glycine serves as a buffering agent, maintaining pH and preventing sample damage during electrophoresis.
Glycine is also used to remove protein-labeling antibodies from Western blot membranes to enable the probing of numerous proteins of interest from SDS-PAGE gel.
This allows more data to be drawn from the same specimen, increasing the reliability of the data, reducing the amount of sample processing, and number of samples required.
This process is known as stripping.

Presence in space
The presence of glycine outside the Earth was confirmed in 2009, based on the analysis of samples that had been taken in 2004 by the NASA spacecraft Stardust from comet Wild 2 and subsequently returned to Earth.
Glycine had previously been identified in the Murchison meteorite in 1970.
The discovery of glycine in outer space bolstered the hypothesis of so called soft-panspermia, which claims that the "building blocks" of life are widespread throughout the universe.
In 2016, detection of glycine within Comet 67P/Churyumov–Gerasimenko by the Rosetta spacecraft was announced.

The detection of glycine outside the Solar System in the interstellar medium has been debated.
In 2008, the Max Planck Institute for Radio Astronomy discovered the spectral lines of a glycine precursor (aminoacetonitrile) in the Large Molecule Heimat, a giant gas cloud near the Galactic Center in the constellation Sagittarius.

Evolution
Glycine is proposed to be defined by early genetic codes.
For example, low complexity regions (in proteins), that may resemble the proto-peptides of the early genetic code are highly enriched in glycine.

Molar mass: 75.067 g
Appearance: White solid
Density: 1.1607 g/cm3
Melting point: 233 °C

Solubility in water: 249.9 g/L (25 °C)
Acidity (pKa): 2.34 (carboxyl), 9.6 (amino)
XLogP3: -3.2
Hydrogen Bond Donor Count: 2
Hydrogen Bond Acceptor Count: 3

Rotatable Bond Count: 1
Exact Mass: 75.032028402 g/mol
Monoisotopic Mass: 75.032028402 g/mol
Topological Polar Surface Area: 63.3Ų

Heavy Atom Count: 5
Complexity: 42.9
Covalently-Bonded Unit Count: 1
Compound Is Canonicalized: Yes

Glycine is the simplest (and the only achiral) proteinogenic amino acid, with a hydrogen atom as its side chain.
Glycine has a role as a nutraceutical, a hepatoprotective agent, an EC 2.1.2.1 (glycine hydroxymethyltransferase) inhibitor, a NMDA receptor agonist, a micronutrient, a fundamental metabolite and a neurotransmitter.

Glycine is an alpha-amino acid, a serine family amino acid and a proteinogenic amino acid.
Glycine is a conjugate base of a glycinium.
Glycine is a conjugate acid of a glycinate.
Glycine is a tautomer of a glycine zwitterion.

Glycine is a non-essential, non-polar, non-optical, glucogenic amino acid.
Glycine, an inhibitory neurotransmitter in the CNS, triggers chloride ion influx via ionotropic receptors, thereby creating an inhibitory post-synaptic potential.
In contrast, this agent also acts as a co-agonist, along with glutamate, facilitating an excitatory potential at the glutaminergic N-methyl-D-aspartic acid (NMDA) receptors.
Glycine is an important component and precursor for many macromolecules in the cells.

Glycine is a simple, nonessential amino acid, although experimental animals show reduced growth on low-glycine diets.
The average adult ingests 3 to 5 grams of glycine daily.
Glycine is involved in the body's production of DNA, phospholipids and collagen, and in release of energy.
Glycine levels are effectively measured in plasma in both normal patients and those with inborn errors of glycine metabolism.

Nonketotic hyperglycinaemia (OMIM 606899) is an autosomal recessive condition caused by deficient enzyme activity of the glycine cleavage enzyme system (EC 2.1.1.10).
The glycine cleavage enzyme system comprises four proteins: P-, T-, H- and L-proteins (EC 1.4.4.2, EC 2.1.2.10 and EC 1.8.1.4 for P-, T- and L-proteins).
Mutations have been described in the GLDC (OMIM 238300), AMT (OMIM 238310), and GCSH (OMIM 238330) genes encoding the P-, T-, and H-proteins respectively.

Glycine cleavage system catalyses the oxidative conversion of glycine into carbon dioxide and ammonia, with the remaining one-carbon unit transferred to folate as methylenetetrahydrofolate.
Glycine is the main catabolic pathway for glycine and it also contributes to one-carbon metabolism. Patients with a deficiency of this enzyme system have increased glycine in plasma, urine and cerebrospinal fluid (CSF) with an increased CSF: plasma glycine ratio. (A3412). t is also a fast inhibitory neurotransmitter.

Consumer Uses of Glycine:
Glycine is used in the following products: washing & cleaning products, cosmetics and personal care products, perfumes and fragrances, adhesives and sealants, coating products, anti-freeze products, fillers, putties, plasters, modelling clay, polishes and waxes, biocides (e.g. disinfectants, pest control products), lubricants and greases, air care products and leather treatment products.
Other release to the environment of Glycine is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners) and outdoor use.

Service life of Glycine:
Release to the environment of Glycine can occur from industrial use: industrial abrasion processing with low release rate (e.g. cutting of textile, cutting, machining or grinding of metal) and of articles where the substances are not intended to be released and where the conditions of use do not promote release.

Other release to the environment of Glycine is likely to occur from: outdoor use in long-life materials with low release rate (e.g. metal, wooden and plastic construction and building materials), indoor use in long-life materials with low release rate (e.g. flooring, furniture, toys, construction materials, curtains, foot-wear, leather products, paper and cardboard products, electronic equipment), indoor use in long-life materials with high release rate (e.g. release from fabrics, textiles during washing, removal of indoor paints) and outdoor use in long-life materials with high release rate (e.g. tyres, treated wooden products, treated textile and fabric, brake pads in trucks or cars, sanding of buildings (bridges, facades) or vehicles (ships)).

Glycine can be found in complex articles, with no release intended: vehicles and machinery, mechanical appliances and electrical/electronic products (e.g. computers, cameras, lamps, refrigerators, washing machines). Glycine can be found in products with material based on: metal (e.g. cutlery, pots, toys, jewellery) and plastic (e.g. food packaging and storage, toys, mobile phones).
Glycine is intended to be released from scented: clothes, paper products and CDs.

Widespread uses of Glycine:
Glycine is used in the following products: washing & cleaning products, lubricants and greases, laboratory chemicals, adhesives and sealants, coating products, biocides (e.g. disinfectants, pest control products), polishes and waxes and air care products.
Glycine is used in the following areas: health services, agriculture, forestry and fishing, municipal supply (e.g. electricity, steam, gas, water) and sewage treatment and scientific research and development.

Glycine is used for the manufacture of: food products, chemicals, metals and fabricated metal products.
Other release to the environment of Glycine is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners) and outdoor use.

Formulation or re-packing of Glycine:
Glycine is used in the following products: cosmetics and personal care products, laboratory chemicals, pharmaceuticals, coating products and pH regulators and water treatment products.
Release to the environment of Glycine can occur from industrial use: formulation of mixtures.

Uses at industrial sites of Glycine:
Glycine is used in the following products: pharmaceuticals, laboratory chemicals, washing & cleaning products, pH regulators and water treatment products, perfumes and fragrances and cosmetics and personal care products.
Glycine is used in the following areas: health services, scientific research and development, formulation of mixtures and/or re-packaging, agriculture, forestry and fishing and mining.

Glycine is used for the manufacture of: chemicals, electrical, electronic and optical equipment and food products.
Release to the environment of Glycine can occur from industrial use: as an intermediate step in further manufacturing of another substance (use of intermediates), in the production of articles, in processing aids at industrial sites and as processing aid.

Manufacture of Glycine:
Release to the environment of Glycine can occur from industrial use: manufacturing of the substance.

Glycine is an amino acid that helps build proteins needed for tissue and hormone maintenance.
More glycine may help support heart and liver health, improve sleep, reduce diabetes risk, and reduce muscle loss.

Your body naturally produces glycine from other amino acids, but it’s also found in protein-rich foods and available as a dietary supplement.

Along with being a component of protein, glycine has several other impressive health benefits.

Here are the top 9 health benefits and uses of glycine.

Glycine is one of three amino acids that your body uses to make glutathione, a powerful antioxidant that helps protect your cells against oxidative damage caused by free radicals, which are thought to underlie many diseases.

Without enough glycine, your body produces less glutathione, which could negatively affect how your body handles oxidative stress over time.

In addition, because glutathione levels naturally decline with age, ensuring that you get enough glycine as you get older may benefit your health.

Glycine is also one of three amino acids that your body uses to make a compound called creatine.

Creatine provides your muscles with energy to perform quick, short bursts of activity, such as weightlifting and sprinting.

When combined with resistance training, supplementing with creatine has been shown to increase muscle size, strength and power.

Glycine has also been studied for its beneficial effects on bone health, brain function and neurological conditions like Parkinson’s and Alzheimer’s disease.

While your body naturally creates creatine and it can be obtained through your diet, getting too little glycine may reduce how much you produce.

Collagen is a structural protein that contains high amounts of glycine. In fact, every third to fourth amino acid in collagen is glycine.

Collagen is the most abundant protein in your body.
Glycine provides strength for your muscles, skin, cartilage, blood, bones and ligaments.

Supplementing with collagen has been shown to benefit skin health, relieve joint pain and prevent bone loss.

Therefore, Glycine’s important that you get enough glycine to support your body’s production of collagen.

Many people struggle to get a good night’s rest, either because they have trouble falling or staying asleep.

While there are several ways you can improve your sleep quality, such as not drinking caffeinated beverages late in the day or avoiding bright screens a few hours before bedtime, glycine may also help.

This amino acid has a calming effect on your brain and could help you fall and stay asleep by lowering your core body temperature.

Research in people with sleep issues has shown that taking 3 grams of glycine before bed decreases how long it takes to fall asleep, enhances sleep quality, lessens daytime sleepiness and improves cognition.

For this reason, glycine may be a good alternative to prescription sleeping pills for improving sleep quality at night and tiredness during the day.

Too much alcohol can have damaging effects on your body, especially your liver.

There are three primary types of alcohol-induced liver damage:

Fatty liver: A buildup of fat inside your liver, increasing its size.

Alcoholic hepatitis: Caused by inflammation of the liver resulting from long-term, excessive drinking.

Alcoholic cirrhosis: The final phase of alcoholic liver disease, occurring when the liver cells are damaged and replaced by scar tissue.
Interestingly, research suggests that glycine may reduce the harmful effects of alcohol on your liver by preventing inflammation.

It has been shown to reduce concentrations of alcohol in the blood of alcohol-fed rats by stimulating the metabolism of alcohol in the stomach rather than the liver, which prevented the development of fatty liver and alcoholic cirrhosis.

What’s more, glycine may also help reverse liver damage caused by excessive alcohol intake in animals.

While moderate alcohol-induced liver damage can be reversed by abstaining from alcohol, glycine may improve the recovery process.

In a study in rats with alcohol-induced liver damage, the liver cell health returned to baseline 30% faster in a group fed a glycine containing diet for two weeks compared to a control group.

Despite promising finds, studies on the effects of glycine on alcohol-induced liver damage are limited to animals and cannot be translated to humans.

Increasing evidence suggests that glycine offers protection against heart disease.

Glycine prevents the accumulation of a compound that, in high amounts, has been linked to atherosclerosis, the hardening and narrowing of the arteries.

Glycine may also improve your body’s ability to use nitric oxide, an important molecule that increases blood flow and lowers blood pressure.

Glycine an observational study in over 4,100 people with chest pains, higher levels of glycine were associated with a lower risk of heart disease and heart attacks at a 7.4-year follow-up.

After accounting for cholesterol-lowering medications, the researchers also observed a more favorable blood cholesterol profile in people who had higher glycine levels.

What’s more, glycine has been found to reduce several risk factors of heart disease in rats fed a high-sugar diet.

Eating and drinking too much added sugar can raise blood pressure, increase levels of fat in your blood and promote dangerous fat gain around the belly — all of which can promote heart disease.

While encouraging, clinical studies on the effects of glycine on heart disease risk in humans are needed before it can be recommended.

Type 2 diabetes may lead to low levels of glycine.

It’s a condition characterized by impaired insulin secretion and action, meaning your body doesn’t produce enough insulin or that it doesn’t respond properly to the insulin it makes.

Insulin decreases your blood sugar levels by signaling its uptake into cells for energy or storage.

Interestingly, because glycine has been shown to increase insulin response in people without diabetes, it’s suggested that glycine supplements may improve impaired insulin response in people with type 2 diabetes.

Higher levels of glycine are associated with a reduced risk of type 2 diabetes, even after accounting for other factors that are associated with the condition, such as lifestyle.

Therefore, people with type 2 diabetes may benefit from supplementing with glycine, though research is too preliminary to make any specific recommendations.

If you have type 2 diabetes, the best way to reduce your insulin resistance is through weight loss by means of diet and exercise.

Glycine may reduce muscle wasting, a condition that occurs with aging, malnutrition and when your body is under stress, such as with cancer or severe burns.

Muscle wasting leads to a harmful reduction in muscle mass and strength, which declines functional status and can complicate other potentially present diseases.

The amino acid leucine has been studied as a treatment for muscle wasting, as it strongly inhibits muscle breakdown and enhances muscle building.

However, several changes in the body during muscle-wasting conditions impair the effectiveness of leucine for stimulating muscle growth.

Interestingly, in mice with muscle wasting conditions, such as cancer, research has shown that glycine was able to stimulate muscle growth whereas leucine was not.

Therefore, glycine holds promise for improving health by protecting muscles from wasting during various wasting conditions.

Still, more research in humans is needed.

Glycine is found in varying amounts in meat, especially in tough cuts like the chuck, round and brisket.

You can also get glycine from gelatin, a substance made from collagen that’s added to various food products to improve consistency.

Other and more practical ways to increase your intake of glycine include:

Add It to Foods and Drinks
Glycine is readily available as a dietary supplement in capsule or powder form.
If you don’t like taking pills, the powder form dissolves easily in water and has a sweet taste.

In fact, the name glycine is derived from the Greek word for “sweet.”

Due to its sweet taste, you can easily incorporate glycine powder into your diet by adding it to:
Coffee and tea
Soups
Oatmeal
Protein shakes
Yogurt
Pudding

Take Collagen Supplements
Glycine is the main amino acid in collagen, the main structural protein of connective tissue, such as bone, skin, ligaments, tendons and cartilage.

Accordingly, you can boost your glycine intake by taking collagen protein supplements.

This is likely more efficient, as glycine competes with other amino acids for absorption and is therefore absorbed less efficiently by itself than when it’s bound to other amino acids, as in the case of collagen.

Supplementing with glycine is safe in appropriate amounts.

Studies have used up to 90 grams of glycine per day over several weeks without serious side effects.

For comparison, the standard dose used in studies is about 3–5 grams per day.

Glycine is an amino acid with many impressive health benefits.

Your body needs glycine to make important compounds, such as glutathione, creatine and collagen.

This amino acid may also protect your liver from alcohol-induced damage and improve sleep quality and heart health.

What’s more, glycine may also benefit people with type 2 diabetes and protect against muscle loss that occurs with muscle-wasting conditions.

You can increase your intake of this important nutrient by eating some meat products, by adding the powdered supplement form to drinks and foods or by supplementing with collagen.

Glycine is an amino acid with a number of important functions in the body.
Glycine acts as a neurotransmitter, a component of collagen, and as a precursor to various biomolecules (e.g., creatine, heme), among other roles.

Glycine is often considered conditionally essential, meaning it can usually be produced in the body in sufficient amounts.
However, in certain contexts (e.g., pregnancy) more glycine may be needed from the diet.
Glycine is found in most protein sources, meaning common sources of glycine include meat, eggs, soybeans, lentils, and dairy products.

A few studies have found supplementation with glycine can improve sleep quality, with subsequent benefits to cognitive function.
High doses of glycine have been shown to improve symptoms of schizophrenia.
Glycine may reduce the blood glucose response to carbohydrate ingestion.
Glycine is a major component of collagen (around 25% by weight) and for this reasons is often taken to improve joint health, but human evidence in this area is currently lacking.

In high amounts, glycine supplementation can cause gastrointestinal symptoms, including nausea and abdominal pain.

Glycine supplementation likely works through different mechanisms depending on the outcome of interest.

Glycine is a co-agonist of N-methyl-D-aspartate (NMDA) receptor, meaning glycine plays a role in activating this receptor in the brain.
Glycine’s effect on the NMDA receptor has been proposed as underlying the improvements in both sleep and symptoms of schizophrenia with supplementation.
Glycine may benefit sleep by lowering core body temperature, as a warm body temperature can adversely affect sleep quality.

Glycine is an amino acid, a building block for protein.
Glycine is not considered an “essential amino acid” because the body can make it from other chemicals.
A typical diet contains about 2 grams of glycine daily.
The primary sources are protein-rich foods including meat, fish, dairy, and legumes.

Glycine is used for treating schizophrenia, stroke, benign prostatic hyperplasia (BPH), and some rare inherited metabolic disorders. It is also used to protect kidneys from the harmful side effects of certain drugs used after organ transplantation as well as the liver from harmful effects of alcohol. Other uses include cancer prevention and memory enhancement.

Some people apply glycine directly to the skin to treat leg ulcers and heal other wounds.

The body uses glycine to make proteins.
Glycine is also involved in the transmission of chemical signals in the brain, so there is interest in trying it for schizophrenia and improving memory.
Some researchers think glycine may have a role in cancer prevention because it seems to interfere with the blood supply needed by certain tumors.

Glycine is a major amino acid in mammals and other animals.
Glycine is synthesized from serine, threonine, choline, and hydroxyproline via inter-organ metabolism involving primarily the liver and kidneys.
Under normal feeding conditions, glycine is not adequately synthesized in birds or in other animals, particularly in a diseased state.
Glycine degradation occurs through three pathways: the glycine cleavage system (GCS), serine hydroxymethyltransferase, and conversion to glyoxylate by peroxisomal D-amino acid oxidase.

Among these pathways, GCS is the major enzyme to initiate glycine degradation to form ammonia and CO2 in animals.
In addition, glycine is utilized for the biosynthesis of glutathione, heme, creatine, nucleic acids, and uric acid.
Furthermore, glycine is a significant component of bile acids secreted into the lumen of the small intestine that is necessary for the digestion of dietary fat and the absorption of long-chain fatty acids.

Glycine plays an important role in metabolic regulation, anti-oxidative reactions, and neurological function. Thus, this nutrient has been used to: prevent tissue injury; enhance anti-oxidative capacity; promote protein synthesis and wound healing; improve immunity; and treat metabolic disorders in obesity, diabetes, cardiovascular disease, ischemia-reperfusion injuries, cancers, and various inflammatory diseases.

These multiple beneficial effects of glycine, coupled with its insufficient de novo synthesis, support the notion that it is a conditionally essential and also a functional amino acid for mammals.

Glycine is a non-essential amino acid that is produced naturally by the body.
Glycine is one of 20 amino acids in the human body that synthesize proteins, and it plays a key role in the creation of several other important compounds and proteins.

Glycine has been shown to be safe as a dietary supplement, although a healthy and varied diet will typically provide the necessary amounts of glycine the body needs.

The primary function glycine takes on in the body is to synthesize proteins.
However, Glycine is also essential for the healthy development of the skeleton, muscles, and tissues.

Glycine benefits for bone health
Although the impact of specific amino acids on bone mineral density and the risk of bone diseases such as osteoporosis has not been identified, glycine has been implicated in promoting bone health.

Glycine is thought that glycine (among other non-essential amino acids) helps bone health through the production of insulin and insulin-like growth factor 1, along with the synthesis of collagen, which is an important protein for bone, tissue, and muscle health throughout the body.

Glycine benefits for muscle health
Glycine can prevent muscles from breaking down by boosting the level of creatine in the body, which is a compound found in muscle cells and made by glycine and two other amino acids.

Boosting creatine in the muscles can help them to perform better in short, intense bursts of activity such as weightlifting or sprinting.
Several studies have shown that boosting creatine in the body can lead to increased muscle strength, mass, and power, and it may also help with recovery after exercise and rehabilitation after injury.

One study found that a daily dose of 5 g to 20 g of creatine meant that patients requiring one injured leg to be kept in a cast for 2 weeks experienced less muscle atrophy due to inactivity, and they gained more strength from their rehabilitation exercises than those not taking creatine.

As a result, glycine is a popular supplement for bodybuilders and those wishing to gain muscle mass and strength.
However, the body can synthesize creatine itself and can be taken in through the diet, so glycine supplements to boost creatine levels may not always be necessary.

Glycine is found in high amounts in collagen, which is a structural protein that promotes strength and elasticity in the skin.
Glycine is the main element that makes up the fascia, cartilage, ligaments, tendons, and bones, and is the most abundant protein in the human body.

Glycine supplements have been shown to reduce the levels of bone loss in osteopenic postmenopausal women, reduce joint deterioration in athletes experiencing joint pain, and increase skin elasticity in older women.

Glycine benefits for sleep
3 g of glycine a day before sleep has been found to improve sleep quality and reduce feelings of fatigue during the day in people with insomnia or those who do not have much time to sleep.

Glycine injections in animal studies have been shown to limit the activity of neurons that are responsible for arousal and energy homeostasis, and glycine injections have also been found to encourage non-REM sleep in mice, although the link between glycine and neuronal activity blocking of this kind is disputed.

Sleep may also be improved with glycine because it decreases the body’s core temperature, and cooler body temperatures are linked with better quality sleep.

Glycine is believed that glycine supplementation activates N-methyl-D-aspartate (NMDA) receptors in the suprachiasmatic nucleus (SCN) and leads to better thermoregulation and circadian rhythm, although the mechanisms through which glycine activates NMDA receptors in the SCN to induce better sleep are not yet understood.

Glycine is also an inhibitory neurotransmitter in the central nervous system and plays a role in the processing of motor and sensory information.
Glycine is found in the spinal cord, the brainstem, and the retina, and can both inhibit and promote excitability in various neurotransmitters.

This can be helpful and dangerous depending on the strength of inhibition or excitation and the dose of glycine.

If a dose of glycine is too high, it can cause fatal hyperexcitability in the brain, but highly inhibited glycine can cause muscular convulsions and asphyxia, causing death.
This is because glycine receptors can be blocked by strychnine, which in high amounts causes these fatal complications.

However, the inhibitory functions of glycine help manage psychological conditions such as schizophrenia, and glycine has become a potential therapeutic route for the management of schizophrenia symptoms.

Glycine can increase the neurotransmission of NMDA, and low levels of NMDA receptors have been reported as a possible contributing factor to the development of schizophrenia.
Glycine is safe for short- and long-term use, and as such it is a possible effective treatment for the symptoms of schizophrenia.

Literature reviews have found that creatine supplements may improve short-term memory function and the reasoning capabilities in healthy people, although its benefits on those living with dementia or other degenerative cognitive diseases have not been fully ascertained.

Related to glycine’s role in the creation of creatine, it has been widely documented that creatine has neuroprotective properties.
Animal studies investigating the benefits of creatine supplementation on traumatic brain injuries (TBI), cerebral ischemia, and spinal cord injuries (SCI) have found that creatine can improve the level of damage to the cortical region from 36 to 50 percent, and in rats with spinal cord injuries, creatine supplementation improved locomotor function.

As it has been proven safe to consume as a supplement, creatine supplementation could, therefore, have potential as a therapeutic agent in humans to treat TBI and SCI.

Although glycine is made naturally by the body, it can also be found in a range of common foods, including meat, fish, dairy products, and legumes.
These protein-rich foods should provide the body with enough glycine to function healthily without the need for glycine supplementation.

Glycine supplements are made in powders or capsules, and powders are often added to food and drinks because of their naturally sweet taste.

Although glycine is the simplest amino acid, it has a complex array of functions and effects on the body. While it can inhibit certain neurotransmitters that can improve certain psychological conditions, it can also excite neurotransmitters that cause muscular convulsions and potentially fatal brain hyperexcitability.

Glycine is safe to consume as a dietary supplement in appropriate doses, both for short- and long-term use, however, the body will usually receive the right amount of glycine from a varied, healthy diet.
Glycine has a range of benefits that include the bones, tissues, muscles, and central nervous system, and as such is one of the most important non-essential amino acids in the body.

In estimating the pKa of a functional group, it is important to consider the molecule as a whole.
For example, glycine is a derivative of acetic acid, and the pKa of acetic acid is well known.
Alternatively, glycine could be considered a derivative of aminoethane.

Builds muscle
Glycine is required for the synthesis of creatine, a chemical that provides energy to your muscles and helps with increasing muscle strength and size.

Repairs joints
Glycine is the main amino acid in collagen, which is crucial for your joints, tendons, and ligaments.
Glycine has been demonstrated in studies to be necessary for the creation of flexible cartilage, help heal injured joints, and prevent the loss of mobility and functionality in older people.

Reduces inflammation
Glycine is a dietary precursor to glutathione, a powerful antioxidant that plays a role in lowering inflammation and protecting against free radical damage.
By inhibiting the generation of harmful inflammatory molecules, glycine can help prevent diseases linked to oxidative stress such as liver injury, ischemic stroke, and heart attack.

Protects the liver from alcohol damage
Excessive alcohol use can be damaging to the liver.
By preventing inflammation, glycine can help minimize the detrimental effects of alcohol on the liver.
Animal studies have shown that glycine may help reduce blood alcohol concentration in rats who were fed alcohol.

Protects heart health
Due to its anti-inflammatory and antioxidant properties, glycine lowers the risk of heart disease.
In a 2015 study published in the Journal of the American Heart Association, researchers examined the relationship between glycine plasma levels and acute myocardial infarction (heart attack). 
tudy subjects included 4,109 people who had undergone elective coronary angiography to rule out stable angina (blockage in the coronary artery).
According to the study, people with higher plasma glycine levels had a lower risk of heart disease and heart attack.

Helps improve metabolic disorders
Glycine is believed to aid in the treatment of diabetes and other metabolic diseases.
Glycine lowers glycated hemoglobin, a risk factor associated with poor blood sugar control in people with type II diabetes.
Glycine also increases the release of a gut hormone (glucagon) that aids insulin in the removal of glucose from the bloodstream. 

In addition, glycine increases adiponectin levels, a chemical that controls satiety and fat metabolism. This may lead to weight reduction in people who are obese, although this effect has only been seen in cell studies.

Improves digestive system
Bone broth has been used for many years to treat digestive issues because it contains high levels of glycine, which promotes the health of the gut wall and mucosa.
Glycine can help speed up the healing of ulcers and regulation of stomach acidity.

Improves sleep quality
Glycine helps activate the N-methyl-D-aspartate (NMDA) receptor in the brain, which may have a calming effect on the brain and lower core body temperature, both of which can help improve symptoms of sleep disorders. 

Builds immunity
Glycine promotes the synthesis of glutathione, an essential antioxidant that protects cells against free radicals, peroxide (a molecule that binds to the radicals), and lipid peroxidation (oxidative stress of lipids).
By protecting your body against oxidative stress, glycine can help boost your immune system.

Glycine is the smallest of the amino acids.
Glycine is ambivalent, meaning that it can be inside or outside of the protein molecule.
In aqueous solution at or near neutral pH, glycine will exist predominantly as the zwitterion

The isoelectric point or isoelectric pH of glycine will be centered between the pKas of the two ionizable groups, the amino group and the carboxylic acid group.