AMINOETHANOIC ACID

DESCRIPTION
Aminoethanoic acid, commonly known as glycine, is the simplest amino acid and is an essential component in various biological processes. 
Its chemical formula is NH₂CH₂COOH, consisting of an amino group (-NH₂), a carboxylic acid group (-COOH), and a single hydrogen atom as its side chain. 
This simplicity makes glycine unique among amino acids, as it is achiral
 
Cas Number: 56-40-6
 
SYNONYMS
Glycine,Aminoacetic acid,2-Aminoacetic acid,Gly ,Glycocoll,Aci-nitroethane
 
Aminoethanoic acid, commonly known as glycine, is the simplest of all amino acids and holds significant importance in both biochemistry and medicine. 
Its structure consists of an amino group (-NH₂) and a carboxyl group (-COOH) attached to a single carbon atom, making it a fundamental building block of proteins. 

Despite being non-essential for humans, glycine plays crucial roles in metabolism, neurotransmission, and the synthesis of proteins, collagen, and other biomolecules. 
This paper delves into the structure and properties of glycine, its biosynthesis and metabolic pathways, its biological significance in human health, and its diverse applications in nutrition, medicine, and industry. 

Recent advances in glycine research have revealed its potential as a therapeutic agent for various health conditions. 
This article aims to provide an exhaustive overview of glycine’s roles, applications, and current research trends.
 

Glycine, or aminoethanoic acid, is the smallest amino acid by molecular weight and an essential metabolite in living organisms. 
It was first isolated in 1820 by Henri Braconnot, who derived it from gelatin. 
Over the years, its role in biochemistry has expanded, showing involvement in numerous physiological processes, including protein synthesis, neurotransmission, and the detoxification of harmful substances. 

Glycine is a non-essential amino acid in humans, meaning it can be synthesized endogenously from precursors such as serine. 
This versatility has led to its use in various industrial, nutritional, and medical applications. 
This review explores the molecular structure, biosynthesis, biological functions, and applications of glycine, highlighting its significance across multiple fields.
 
Chemical Structure and Properties
Glycine has the molecular formula C₂H₅NO₂. 
The molecule consists of an amino group (-NH₂), a carboxyl group (-COOH), and a hydrogen atom attached to the central carbon. 

This structure distinguishes glycine from other amino acids, as it does not contain a side chain or "R group" typically found in other amino acids. 
This lack of complexity contributes to glycine’s small molecular size.
 
Functional Groups:
Amino group (-NH₂): A basic group capable of accepting a proton, making glycine a weak base.
Carboxyl group (-COOH): An acidic group capable of donating a proton, allowing glycine to act as an acid in solution.
Hydrogen atom (H): This feature of glycine makes it unique among the 20 standard amino acids, as it does not have a larger side chain.
Physical Properties:
Melting point: Approximately 232°C (decomposes).
Solubility: Glycine is highly soluble in water due to its ionic nature in aqueous environments. 

Its solubility is enhanced by the hydrophilic nature of its functional groups.
Optical Activity: Glycine is optically inactive because it lacks a chiral center (no asymmetric carbon).
Chemical Reactivity:
Glycine can undergo peptide bond formation, linking with other amino acids to form peptides and proteins.

It also participates in various enzymatic reactions as a substrate or cofactor.
Comparison with Other Amino Acids:
Unlike most amino acids, glycine lacks a side chain, making it achiral. 
It is also the only amino acid that can fit into tight spaces in protein structures due to its small size and lack of steric hindrance.
 
Biosynthesis of Glycine
Glycine is synthesized in the body through two main pathways: the serine hydroxymethyltransferase (SHMT) pathway and the glycine decarboxylase (GDC) pathway.
 
SHMT Pathway:
This is the primary route for glycine biosynthesis. 
Serine, an amino acid, is converted into glycine by the enzyme serine hydroxymethyltransferase. 
This reaction requires the cofactor tetrahydrofolate (THF), which transfers a one-carbon unit to the reaction, resulting in the formation of glycine.
 
GDC Pathway:
This pathway occurs primarily in mitochondria, where glycine decarboxylase catalyzes the decarboxylation of glycine, producing carbon dioxide and a one-carbon unit that can be utilized in various metabolic processes. 
This pathway is critical for the regulation of folate metabolism and one-carbon metabolism.
 
Regulation of Glycine Synthesis:
The synthesis of glycine is tightly regulated by the body based on cellular and metabolic needs. 
Deficiencies in enzymes responsible for glycine synthesis or degradation can lead to metabolic disorders.
 
Metabolism and Biochemical Pathways
Glycine plays a key role in several metabolic pathways, especially those related to one-carbon metabolism, detoxification, and protein synthesis.
 
One-Carbon Metabolism:
Glycine is a central player in the one-carbon metabolic cycle, which is involved in DNA synthesis, methylation reactions, and amino acid interconversion. 
In this cycle, glycine can be interconverted with serine and participate in the transfer of one-carbon units necessary for purine and thymidylate biosynthesis.
 
Glycine’s Role in Collagen Synthesis:
Glycine is essential for collagen formation, making up approximately one-third of the collagen protein. 
This role is crucial in connective tissue, skin, cartilage, and bone health.
 
Synthesis of Other Compounds:
Glycine is a precursor for several important compounds, including:
 
Porphyrins (precursors to heme)
Creatine (important for muscle function)
Glutathione (a potent antioxidant)
Purines (components of DNA and RNA)
 
Biological Significance and Functions
Glycine performs several vital biological functions:
 
Neurotransmission:
Glycine acts as an inhibitory neurotransmitter in the central nervous system, primarily within the spinal cord and brainstem. 
It functions by binding to glycine receptors, which are ligand-gated chloride channels that mediate inhibitory signaling. 
Glycine’s inhibitory effects help modulate motor control and pain perception.
 
Collagen Synthesis:
As a major constituent of collagen, glycine contributes to the structural integrity of tissues. 
The high glycine content in collagen enables the formation of the triple helix structure that provides strength and elasticity to connective tissues.
 
Detoxification:
Glycine conjugates with toxic substances in the liver to form water-soluble compounds, which are more easily excreted via the urine. 
This process aids in detoxification and waste elimination.
 
Glycine in Human Health and Disease
While glycine is vital for normal biological processes, its deficiency or imbalance can lead to various health issues:
 
Glycine Deficiency Disorders:
Nonketotic Hyperglycinemia (NKH): A rare genetic disorder characterized by elevated glycine levels in the blood and cerebrospinal fluid, leading to neurological symptoms such as seizures and developmental delay.

Hypoglycinemia: A condition with abnormally low glycine levels, leading to symptoms such as lethargy, fatigue, and muscle weakness.
Role in Metabolic Diseases:
Glycine is implicated in the regulation of insulin sensitivity and glucose metabolism, with some studies suggesting that glycine supplementation may have therapeutic potential for diabetes and metabolic syndrome.
As an antioxidant, glycine may help mitigate oxidative stress associated with obesity and cardiovascular diseases.

Neurodegenerative Diseases:
Glycine’s neuroprotective properties have been explored in conditions like Parkinson’s disease, Alzheimer’s, and ALS, where it may help reduce excitotoxicity and promote neuronal survival.
 
Glycine in Nutrition and the Food Industry
Glycine is naturally found in many protein-rich foods, particularly those high in collagen, such as meat, fish, and dairy products. 
It is often consumed in gelatin form, which is rich in glycine.
 
Dietary Sources:
Animal products such as meat, fish, and dairy
Gelatin and collagen supplements
Legumes and certain seeds (though in lower amounts)
Supplementation:
Glycine supplementation is used in various therapeutic contexts, including the management of sleep disorders, metabolic syndrome, and neurological health. It is also used as a flavor enhancer in food processing.
 
Industrial Applications of Glycine
Glycine’s versatility extends beyond biochemistry and medicine, with significant uses in the pharmaceutical, cosmetic, and agricultural industries:
 
Pharmaceuticals:
Glycine is used as a buffering agent in injectable medications and intravenous solutions. 
It also serves as a stabilizer in formulations of certain drugs.
 
Agriculture:
In agriculture, glycine is a component in some herbicide formulations, enhancing the effectiveness of these chemicals.
 
Cosmetics:
Due to its moisturizing and soothing properties, glycine is used in skincare products, including creams and lotions.
 
Biotechnology:
Glycine plays a role in cell culture media for the growth and maintenance of mammalian cells, making it essential in biomanufacturing.
 
Analytical Techniques for Glycine
Several techniques are available for the analysis and quantification of glycine in biological samples:
 
Chromatography:
High-Performance Liquid Chromatography (HPLC): Used for the separation and quantification of glycine in complex mixtures.
Thin-Layer Chromatography (TLC): A simpler technique used for qualitative analysis.

Spectroscopy:
Nuclear Magnetic Resonance (NMR): Provides detailed structural information about glycine and its interactions with other molecules.
Mass Spectrometry: Used for the precise measurement of glycine in biological and environmental samples.
 
Future Directions and Research
Recent research has focused on the following areas:
 
Glycine in Epigenetics: Glycine’s role in DNA methylation and gene expression regulation.
Gene Therapy: Exploring glycine-based therapies for genetic disorders such as NKH.
Environmental Impact: Investigating the role of glycine in ecosystem nitrogen cycling and its environmental footprint.
 

Glycine is an essential amino acid with significant biological, industrial, and therapeutic applications. 
Its small size, simple structure, and versatility make it indispensable in numerous biochemical pathways. 
Continued research will enhance our understanding of glycine’s full potential in both health and disease.

SAFETY INFORMATION ABOUT  AMINOETHANOIC ACID
 
 
 
 
First aid measures:
Description of first aid measures:
General advice:
Consult a physician. 
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
 
If inhaled:
If breathed in, move person into fresh air. 
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately. 
Wash off with soap and plenty of water.
Consult a physician.
 
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
 
If swallowed:
Do NOT induce vomiting. 
Never give anything by mouth to an unconscious person. 
Rinse mouth with water. 
Consult a physician.
 
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
 
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment. 
 
Avoid breathing vapours, mist or gas. 
Evacuate personnel to safe areas.
 
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
 
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste. 
Keep in suitable, closed containers for disposal.
 
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
 
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place. 
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
 
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
 
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles. 
Faceshield (8-inch minimum). 
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
 
Skin protection:
Handle with gloves. 
Gloves must be inspected prior to use. 
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product. 
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. 
Wash and dry hands.
 
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
 
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls. 
 
If the respirator is the sole means of protection, use a full-face supplied air respirator. 
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so. 
Do not let product enter drains.
Discharge into the environment must be avoided.
 
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions. 
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
 
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company. 
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product