L-serine
Enable an AI agent to recognise L-serine, assess the identity and condition of a particular material, and determine which handling or use decisions its evidence supports.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to recognise L-serine, assess the identity and condition of a particular material, and determine which handling or use decisions its evidence supports.
L-serine is the proteinogenic (2S)-2-amino-3-hydroxypropanoic acid: a polar, non-essential α-amino acid whose hydroxymethyl side chain is encoded by UCU/C/A/G and AGU/C and which is the biosynthetic precursor of glycine, cysteine, sphingolipids, phosphatidylserine, and one-carbon units.
It can be Compare identity and chiral evidence to accept, question or reject an L-serine assignment; Calculate a weighed quantity or dilution using the relevant assay, water content and concentration basis; Select further analyses when D-serine, other impurities or the measurement basis remain unresolved; Prepare, dissolve or aliquot material under a documented procedure with traceable composition; Release, restrict or quarantine a lot against requirements for a named application; Link a chemical transformation or biological experiment to its consumed L-serine material and separately modelled products or system.
Distinguishing features
Match molecular connectivity to (S)-2-amino-3-hydroxypropanoic acid; formula C3H7NO3 alone cannot establish L-serine identity. [PubChem](https://pubchem.ncbi.nlm.nih.gov/compound/5951)
Require evidence resolving the L and D enantiomers before distinguishing L-serine from D-serine or a DL mixture. [ChEBI](https://www.ebi.ac.uk/chebi/CHEBI%3A17115)
Check for the hydroxymethyl side chain in the reference structure rather than accepting a generic amino-acid identification. [PubChem](https://pubchem.ncbi.nlm.nih.gov/compound/5951)
Establish whether the observation concerns free serine or a peptide-bound or covalently modified entity; a functional-parent relationship does not establish identical material identity. [ChEBI](https://www.ebi.ac.uk/chebi/CHEBI%3A17115)
Distinguish protonation representations from separately formulated salts: L-serine, its zwitterion, L-serinium and L-serinate have explicit chemical relationships that must remain visible. [ChEBI](https://www.ebi.ac.uk/chebi/CHEBI%3A17115)
Scope
+ Identification of free L-serine and discrimination from unspecified serine, D-serine and DL-serine
+ Chemical assay, enantiomeric composition and relevant impurities in L-serine material
+ Solid or dissolved state, water content and solution conditions
+ Lot origin, processing history and evidence supporting grade claims
+ Condition-dependent handling, preparation and fitness for a specified use
- Independent models of D-serine and racemic DL-serine
- Serine residues within peptides and proteins
- Covalently modified serine derivatives and separately identified salt products
- Complete formulations, culture media and biological specimens containing L-serine
- Organism-level serine metabolism, clinical interpretation and treatment decisions
Characteristics
- Chemical identity evidence
- Structure-specific reference linked to an observed identity test Connects the name L-serine to evidence about the material actually present.
- Stereochemical assignment
- L confirmed; L claimed; mixed enantiomers; unresolved; conflicting Prevents an unspecified serine result from being accepted as L-serine.
- Enantiomeric composition
- L and D mole fractions or percentages, with method and quantification limits Makes D-serine content visible independently of total serine assay.
- Serine assay
- Mass %, specifying as-received or dry basis and whether the method resolves enantiomers Avoids treating total serine content as a measurement of L-serine alone.
- Water content
- Mass %, with method and sampling date Supports correct weighing and comparison of assay bases.
- Material presentation
- Solid; solution; suspension; other documented state Determines which sampling, concentration and handling observations are needed.
- Solution concentration
- mol/L or g/L, with solvent, temperature and preparation basis Supports preparation and transfer of a known amount of dissolved L-serine.
- Solution acidity
- pH, with temperature, solvent system and measurement method Provides context for protonation, compatibility and analytical interpretation.
- Non-serine impurity profile
- Named analytes in mass %, mg/kg or method-specific units, including reporting limits Allows impurity acceptance to follow the intended use rather than a single purity label.
- Lot and processing lineage
- Supplier lot, documented production route, certificate and subsequent preparation events Connects observations to the correct material and directs route-specific verification.
- Use-specific disposition
- Unassessed; supported for named use; restricted; quarantined; rejected Expresses an actionable conclusion without treating suitability as a universal property.
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 19 findings · 37 questions.
Serine identity and boundaries Establish what the L-serine designation refers to in the observed material.
Serine names can conceal unresolved stereochemistry, bound residues or distinct chemical products.
Molecular and chiral identity
Separate evidence for serine connectivity from evidence for the L configuration.
Supported L-serine assignment
Record the reference identity, observed analytical agreement and strength of stereochemical assignment.
- Which structure-specific reference defines the material called L-serine? definition
- Which observations establish serine connectivity and which independently resolve L from D? measurement
- Does the identification describe this sample or only repeat its supplier label? provenance
Free serine and related entities
Locate the boundary between L-serine material and related chemical or composite entities.
Entity boundary assignment
State whether the record concerns free L-serine, its solution speciation or a neighbouring entity requiring a relationship.
- Is the measured serine free, peptide-bound or released by sample hydrolysis? boundary
- Are counterions or covalent modifications present that require a separate product identity? boundary
- Which protonation representations belong within this registry entry and which require linked entities? definition
Serine content and selectivity Determine how much L-serine is present and what the analytical results actually distinguish.
Total serine, L-serine content and enantiomeric purity answer different acceptance questions.
Chemical assay and mass basis
Make assay values interpretable for weighing and comparison.
Interpretable serine assay
Record analyte definition, reporting basis, calibration and uncertainty before using an assay quantitatively.
- Does the reported assay quantify L-serine specifically, total serine or a less selective response? measurement
- Is the value a mass fraction, chromatographic area percentage or another quantity, and is it corrected for water? measurement
- What reference standard and uncertainty support conversion from weighed material to L-serine amount? provenance
Enantiomer and impurity resolution
Assess D-serine and other constituents separately from the main assay.
Resolved enantiomeric composition
Determine whether the chiral result supports the required L-serine fraction.
- What L-to-D composition was measured, with what separation performance and quantification limit? measurement
- If optical rotation supports identification, what solvent, concentration, temperature and reference conditions were used? measurement
Use-relevant impurities
Connect impurity coverage to the production route and proposed application.
- Which other amino acids, residual reagents, solvents, inorganic constituents or biological contaminants require investigation for this lot? provenance
- Which impurity results and reporting limits satisfy the named application's acceptance criteria? action
Solid and solution behaviour Describe the material conditions needed to sample, weigh and prepare L-serine reliably.
A solid lot and a prepared solution require different evidence about amount, homogeneity and chemical environment.
Solid material condition
Assess water, physical presentation and sampling representativeness.
Representative solid quantity
Establish whether the sampled solid and its measured mass support the intended preparation.
- What water content and visible heterogeneity were observed in the solid at sampling? measurement
- Do particle form, caking or segregation require a different sampling or dissolution procedure? action
Dissolution and solution speciation
Capture the conditions defining dissolved L-serine and the evidence for a homogeneous preparation.
Defined serine solution
Record solvent, concentration, pH, temperature and additions that determine the usable preparation.
- At the intended concentration, solvent composition and temperature, was complete dissolution demonstrated? measurement
- What pH and acid, base or buffer additions define the solution environment? measurement
- Does the preparation now require a linked mixture record to preserve its full composition? boundary
Lot history and condition retention Connect present L-serine condition to its origin and subsequent handling.
A certificate supports a particular lot and time; later preparation or exposure can require renewed evidence.
Production and certificate lineage
Identify the origin and evidence behind claims about L-serine grade and composition.
Traceable L-serine lot
Associate the material with its actual certificate, production information and verification gaps.
- Which supplier lot and certificate apply to the container or aliquot being assessed? provenance
- What production or purification route is documented, and which claimed attributes remain unverified? provenance
Storage and preparation history
Evaluate whether handling history affects continued reliance on previous results.
Continued condition support
Record relevant exposures and determine whether assay, chiral composition or contamination controls need reassessment.
- What storage, opening, heating, dissolution, pH adjustment or sterilisation events occurred after the last accepted analysis? provenance
- What evidence supports retained L-serine content, stereochemical composition and required cleanliness after those events? measurement
- Which observed change or elapsed interval requires retesting or quarantine under the applicable procedure? action
L-serine use decisions Translate the material evidence into a justified decision for a specified operation.
L-serine identity alone does not establish fitness as a synthesis input, analytical reference, culture ingredient or other material.
Application-specific acceptance
Bind acceptance to concrete requirements for the proposed use.
Supported use disposition
Compare the lot's evidence with the required assay, stereochemical, impurity and handling criteria.
- What operation requires this L-serine, and which specification or protocol governs acceptance? action
- Which requirements for D-serine content, other impurities or biological cleanliness are met, failed or unmeasured? measurement
- Do the remaining evidence gaps permit use, require restrictions or require quarantine? action
Preparation and transformation boundaries
Define the next permitted operation and preserve identity through preparation or chemical consumption.
Justified material operation
Specify the evidence and procedure needed to weigh, dissolve, transfer or consume the material.
- What assay and water corrections are needed to deliver the requested amount of L-serine? action
- Which handling and compatibility instructions apply to this supplied form and planned operation? action
- Will the operation preserve free L-serine, create a mixture or form a distinct product requiring its own model? boundary
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Free crystalline L-serine (commodity amino acid)
- Protein residue Ser/S, including O-phosphoserine sites
- Physiological zwitterion (dominant near pH 7.4)
- Fermentation-derived L-serine
- Protein-hydrolysis-derived L-serine
- Pharmacopeial (USP / Ph. Eur. / JP) grade
- Cell-culture / non-animal-source grade
- Food-additive nutrient and flavouring grade
- Which of these kinds and varieties hold for the sense of L-serine this model covers, and on what evidence? provenance
Identifiers and schemes
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- CAS Registry Number - 56-45-1 - L-serine specifically; racemate is 302-84-1 and D-serine is 312-84-5.
- PubChem CID - 5951 - L-Serine.
- ChEBI - CHEBI:17115 - L-serine (the L-enantiomer of serine).
- Wikidata - Q183290 - Serine item; the proteinogenic default is the L-form.
- UNII (FDA SRS) - 452VLY9402 - L-serine; racemate UNII is 00PAR1C66F.
- EC / EINECS - 200-274-3 - Also ECHA InfoCard 100.000.250.
- InChIKey - MTCFGRXMJLQNBG-REOHCLBHSA-N - Stereospecific key for the L-enantiomer.
- IUPAC-IUB residue symbols - Ser or S - Three- and one-letter codes for the protein residue.
- DrugBank - DB00133 - L-serine drug record.
- KEGG - C00065 - Compound; KEGG DRUG D00016 also applies.
- Which of these identifiers and schemes hold for the sense of L-serine this model covers, and on what evidence? provenance
Standards and regulation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- USP-NF monograph Serine (l-serine) - United States Pharmacopeial Convention
- European Pharmacopoeia serine monograph, (2S)-2-amino-3-hydroxypropanoic acid, product of fermentation or protein hydrolysis - EDQM
- Japanese Pharmacopoeia listing of serine as a drug substance - PMDA / JP
- 21 CFR 172.320 Amino acids, including L-serine as a food-additive nutrient (max 8.4% of total protein as free amino acid) - US FDA
- Food Chemicals Codex L-Serine specifications, incorporated by reference in 21 CFR 172.320 - USP/FCC
- IUPAC-IUB Recommendations 1983 on amino-acid nomenclature and Ser/S symbols - IUPAC-IUB Joint Commission on Biochemical Nomenclature
- REACH/CLP identity EC 200-274-3; typical SDS does not classify L-serine as a GHS hazard - ECHA
- Which of these standards and regulation hold for the sense of L-serine this model covers, and on what evidence? provenance
Real-world use
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Incorporated into proteins as Ser/S; the side-chain hydroxyl is the nucleophile of serine proteases such as trypsin.
- Component of mammalian cell-culture media and of crystalline amino-acid blends for parenteral nutrition.
- US food additive used as a nutrient supplement and as a flavour enhancer/adjuvant under 21 CFR 172.320.
- Industrial manufacture from glycine and methanol using serine hydroxymethyltransferase; sold as USP, Ph. Eur., and non-animal-source grades.
- Oral supplement and investigational agent in L-serine biosynthesis defects and in ALS safety trials (e.g. NCT01835782).
- Metabolic precursor of phosphatidylserine, sphingolipids, glycine, cysteine, and folate one-carbon units.
- Historically isolated from silk protein (sericin) by Emil Cramer in 1865, which gave the compound its name.
- Which of these real-world use hold for the sense of L-serine this model covers, and on what evidence? provenance
Typical measurements
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Molar mass - 105.09 - g·mol−1
- Pharmacopeial assay (USP, dried basis) - 98.5-101.5 - %
- Specific rotation (USP, 2 N HCl) - +14.0 to +15.6 - °
- Loss on drying (105 °C, 3 h, USP) - ≤0.2 - %
- Residue on ignition (USP) - ≤0.1 - %
- Melting / decomposition temperature - 246 (decomposes) - °C
- Density (22 °C) - 1.603 - g·cm−3
- pKa (carboxyl; amino) - 2.21; 9.15 - pKa units
- Food-use cap as free L-serine in protein (21 CFR 172.320) - ≤8.4 - % of total protein by weight
- Acute oral LD50 (rat) - >2000 (also reported 14000) - mg·kg−1
- Which of these typical measurements hold for the sense of L-serine this model covers, and on what evidence? provenance
Failure modes and hazards
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Inherited defects of PHGDH, PSAT or PSPH collapse endogenous L-serine synthesis and present with congenital microcephaly, seizures and severe psychomotor delay.
- Neutral-amino-acid transporter defects similarly starve the CNS of L-serine.
- Enantiomeric contamination with D-serine changes NMDA-receptor pharmacology and fails the pharmacopeial optical-rotation window.
- Related amino-acid impurities, chloride, sulfate, iron and moisture push material out of USP/Ph. Eur. limits.
- The solid decomposes rather than melting cleanly near 246 °C.
- High oral supplemental doses have caused mild, dose-dependent gastrointestinal upset.
- Research reports that the cyanobacterial amino acid BMAA can be misincorporated in place of L-serine, producing misfolded protein; this is a hypothesized, not established, clinical hazard.
- Typical GHS classification is 'not classified'; irritation data on SDS remain incomplete, so handling still follows ordinary laboratory dust and hygiene controls.
- Which of these failure modes and hazards hold for the sense of L-serine this model covers, and on what evidence? provenance
Regional variation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- USP titles the monograph 'Serine' but defines it as l-serine; Ph. Eur. uses the systematic name (2S)-2-amino-3-hydroxypropanoic acid and states origin as fermentation or protein hydrolysis.
- US food use is a listed additive under 21 CFR 172.320; other jurisdictions regulate crystalline amino acids mainly as foods, supplements or pharmaceutical starting materials rather than as a numbered flavouring.
- INN/USAN is serine; Spanish serina and Latin serinum appear in older pharmacopoeial and ChemIDplus synonym lists.
- French Sérine is also a wine-grape name and is not the amino acid.
- Which of these regional variation hold for the sense of L-serine this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- D-serine - Opposite configuration (CAS 312-84-5; InChIKey MTCFGRXMJLQNBG-UWTATZPHSA-N). Separated by specific rotation (L is dextro-rotatory in acid) or chiral HPLC; D-serine is the NMDA co-agonist, not the proteinogenic residue.
- DL-serine (racemate) - CAS 302-84-1; near-zero net optical rotation and a distinct InChIKey (MTCFGRXMJLQNBG-UHFFFAOYSA-N).
- L-threonine - Has a 3-methyl substituent on the hydroxy-bearing carbon; different CAS (72-19-5) and is resolved by amino-acid chromatography or NMR.
- Homoserine - Hydroxy group is on the γ-carbon (HOCH2CH2-) rather than the β-carbon; mass and retention time differ from serine.
- Isoserine - Amino group is on the β-carbon (3-amino-2-hydroxypropanoic acid), not the α-carbon; distinguished by connectivity (NMR/MS) and by not being proteinogenic.
- Glycine - Lacks the hydroxymethyl side chain (C2 vs C3); serine hydroxymethyltransferase interconverts the two, but they separate cleanly on standard amino-acid analysers.
- Sarin - Organophosphorus nerve agent, not an amino acid; Wikipedia disambiguation only. Elemental analysis, IR and mass spectrum are unrelated.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of L-serine this model covers, and on what evidence? provenance
Sources
- Serine - Definition, stereochemistry, biosynthesis, proteinogenic role, identifiers, physical constants, D- versus L-serine biology, serine-deficiency disorders, industrial preparation from glycine and methanol.
- L-Serine | C3H7NO3 | CID 5951 - IUPAC name (2S)-2-amino-3-hydroxypropanoic acid, formula, mass, PubChem CID, InChIKey, MeSH, food-additive and drug database crosswalks.
- L-serine (CHEBI:17115) - ChEBI definition as the L-enantiomer of serine; roles as proteinogenic amino acid and human metabolite; KEGG, DrugBank, HMDB cross-references.
- USP-NF monograph: Serine - Pharmacopeial identity of Serine as l-serine CAS 56-45-1; assay 98.5-101.5% on the dried basis; specific rotation, loss on drying, residue on ignition, iron and related-compound limits.
- 21 CFR § 172.320 - Amino acids - US food-additive listing of L-serine as a nutrient amino acid, FCC specification pointer, and maximum 8.4% of total protein as free L-serine.
- Substances Added to Food: L-SERINE - FDA technical effects: flavour enhancer, flavouring agent or adjuvant, nutrient supplement; CAS 56-45-1; citation of 21 CFR 172.320.
- Safety Data Sheet: L-Serine (USP Reference Standard 1612506) - CAS 56-45-1, not GHS-classified as a physical or health hazard, rat oral LD50 >2000 mg/kg (also reported 14000 mg/kg).
What the second pass must settle
- Does an existing Vercy world model already own L-serine, and what registry boundary should apply to its protonation forms and salt products?
- Which authoritative analytical procedures adequately distinguish L-serine content, total serine assay and low-level D-serine for each intended application?
- What measured solubility and solution-stability evidence applies across the solvents, concentrations, pH values and temperatures actually required?
- Which storage and processing conditions measurably change water content, assay, stereochemical composition or contamination status, and what retest intervals are justified?
- Which current application-specific specifications establish acceptable impurity limits, grade claims and handling requirements for the supplied material?