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L-Serine is a non-essential, polar amino acid that plays a critical role in metabolism, biomolecule synthesis, and cellular signaling.
Classified as a proteinogenic amino acid, it is one of the 20 standard amino acids incorporated into proteins during translation.
Although non-essential in adults, it is considered conditionally essential under certain pathological or developmental conditions, such as neurological disorders or metabolic deficiencies.
CAS Number: 56-45-1
Molecular Formula: C₃H₇NO₃
Molecular Weight: 105.09 g/mol
Synonyms:
(S)-2-Amino-3-hydroxypropanoic acid,Serine (L-form),L-2-Amino-3-hydroxypropionic acid,L-α-Amino-β-hydroxypropionic acid,Ser
Historical Background and Discovery
Serine was first isolated in 1865 from silk protein (sericin), which inspired its name.
Its stereochemistry and structure were elucidated in the early 20th century, and it was recognized as an important amino acid in enzymology, particularly in the active sites of serine proteases (trypsin, chymotrypsin, elastase).
Chemical and Physical Properties
Chemical Formula: C₃H₇NO₃
Molecular Weight: 105.09 g/mol
Appearance: White crystalline solid
Melting Point: 222–228 °C (decomposes)
Solubility: Highly soluble in water, sparingly soluble in alcohol
Isoelectric Point (pI): ~5.68
pKa Values:
pKa1 (carboxyl group): ~2.2
pKa2 (amino group): ~9.2
pKa3 (hydroxyl group): ~13.0
The hydroxyl side chain provides hydrogen bonding potential, contributing to structural stabilization in proteins and enzymatic catalysis.
Biosynthesis of L-Serine
Glycolytic Pathway (Phosphorylated Pathway)
The primary route derives L-serine from the glycolytic intermediate 3-phosphoglycerate via three enzymatic steps:
3-Phosphoglycerate dehydrogenase (PHGDH)
Phosphoserine aminotransferase (PSAT1)
Phosphoserine phosphatase (PSPH)
Non-Phosphorylated Pathway
Alternative routes involve transamination of hydroxypyruvate or serine hydroxymethyltransferase activity.
From Glycine and Threonine
Serine can be synthesized from glycine via serine hydroxymethyltransferase (SHMT), which links it directly to one-carbon metabolism, essential for nucleotide biosynthesis.
Catabolism and Metabolic Fate
Conversion to Glycine: Via SHMT with tetrahydrofolate (THF).
One-Carbon Metabolism: Provides methyl groups for purines, thymidine, and methionine.
Sphingolipid Biosynthesis: Serine combines with palmitoyl-CoA to form 3-ketosphinganine, a precursor of sphingolipids.
Role in Protein Structure and Function
Constitutes ~6% of amino acids in proteins.
Hydroxyl group allows hydrogen bonding and stabilizes tertiary structures.
Site of O-linked glycosylation and phosphorylation, critical in signaling pathways.
Active site residue in serine proteases and serine hydrolases.
Biological Functions
Precursor for glycine, cysteine, sphingolipids, phosphatidylserine.
Involved in CNS development, neuronal growth, and D-serine (NMDA receptor co-agonist).
Enhances immune system via nucleotide and protein biosynthesis.
Participates in metabolic regulation and cell signaling.
Industrial Production of L-Serine
Fermentation with engineered E. coli is the most common method.
Overexpression of PHGDH, PSAT1, PSPH improves yields.
Enzymatic synthesis via hydroxypyruvate reductase.
Chemical synthesis less favored due to stereoselectivity challenges.
Analytical Determination
HPLC with pre-column derivatization (OPA, FMOC).
LC-MS/MS for precise quantification in biological fluids.
NMR spectroscopy for metabolic flux studies.
Enzymatic assays using serine dehydratase.
Nutritional Aspects
Rich sources: soy protein, eggs, fish, nuts, legumes.
Conditional essentiality in infants and patients with metabolic defects.
Incorporated into medical nutrition formulas for cognitive and immune support.
Clinical Significance and Medical Applications
Serine deficiency disorders cause microcephaly, seizures, and psychomotor retardation.
Supplementation may benefit ALS, Alzheimer’s, schizophrenia, epilepsy.
Investigated in neuroprotective therapies.
Role in Cancer Biology
Cancer cells upregulate serine biosynthesis (PHGDH amplification).
Serine contributes to nucleotide synthesis and redox balance.
Targeting serine metabolism is a therapeutic strategy in oncology.
Biotechnology Applications
Used in fermentation media as a nitrogen and carbon source.
Precursor in the production of biodegradable polymers.
Starting material for pharmaceutical intermediates.
SAFETY INFORMATION ABOUT L-SERINE
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
