L-threonine
Enable an AI agent to recognise L-threonine, assess the identity and condition of a particular material, and determine whether it is suitable for a specified use.
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-threonine, assess the identity and condition of a particular material, and determine whether it is suitable for a specified use.
L-Threonine is the (2S,3R) stereoisomer of 2-amino-3-hydroxybutanoic acid, an essential proteinogenic amino acid that cannot be synthesized de novo in humans and other animals and must be obtained from diet or microbial/industrial production.
It can be Match a labelled material to L-threonine using chemical and stereochemical evidence.; Request additional analysis when identity, assay basis or stereoisomer resolution is insufficient.; Calculate a required material quantity from verified L-threonine content and water basis.; Prepare and verify an L-threonine solution under documented conditions.; Accept, restrict or quarantine a lot against requirements for a specified use.; Trigger reassessment after storage excursions, contamination or unexplained changes..
Distinguishing features
Require evidence for (2S,3R)-2-amino-3-hydroxybutanoic acid; a label saying only 'threonine' does not establish this stereochemical identity. Reference: [PubChem L-Threonine](https://pubchem.ncbi.nlm.nih.gov/compound/6288).
Use an identity method capable of establishing molecular connectivity; molecular formula or mass alone cannot establish L-threonine identity.
Require a stereochemically discriminating method to distinguish L-threonine from D-threonine, allothreonine and stereoisomer mixtures.
Distinguish free L-threonine measurements from threonine measured after peptide or protein hydrolysis.
Check whether the material is free L-threonine, a solution containing it, or a separately identified salt or covalent derivative before assigning the registry identity.
Scope
+ L-threonine molecular identity and stereochemical discrimination
+ Evidence connecting a sample or lot to the registered substance
+ L-threonine content, stereochemical purity and relevant impurities
+ Solid or dissolved state and conditions affecting material usability
+ Evidence supporting handling, preparation and use-specific acceptance
- D-threonine, allothreonine and other amino acids as independently modelled substances
- Covalently modified L-threonine derivatives and separately identified salts
- Peptide and protein structures containing threonine residues
- Complete formulations, foods, feeds and culture media containing L-threonine
- Organism metabolism, nutritional requirements and clinical treatment decisions
- Manufacturing equipment and complete fermentation or synthesis processes
Characteristics
- Chemical identity evidence
- Sample-linked identity results, reference material and analytical method Connects the registered substance to observed material rather than relying on a product name.
- Stereochemical identity
- Confirmed (2S,3R), mixed stereoisomers, inconsistent or unresolved Determines whether the material matches L-threonine specifically.
- L-threonine assay
- Mass fraction in %, with as-received or dry basis and method stated Supports quantity calculations without confusing material mass with L-threonine mass.
- Stereoisomer impurity profile
- Fraction of each resolved stereoisomer, with reporting basis and detection limits A total threonine assay may not establish the fraction that is L-threonine.
- Water content
- Mass fraction in %, with method and sampling date Affects assay interpretation and preparation of quantities by weighing.
- Material presentation
- Solid, dissolved, partially dissolved or unresolved; solvent recorded where applicable Determines how the material can be sampled, transferred and prepared.
- Dissolved L-threonine concentration
- g/L or mol/L, with solvent, temperature and preparation basis Supports reproducible use of solutions.
- Solution pH
- pH with temperature and solution composition Provides context for solution behaviour and compatibility.
- Non-stereoisomer impurities
- Named analytes in mg/kg or %, with method and reporting limits Supports acceptance against the requirements of the intended use.
- Lot evidence
- Supplier, lot, sample, certificate, test results and storage history Establishes which material the identity and quality claims describe.
- Use-specific disposition
- Unassessed, accepted, restricted, quarantined or rejected against a named specification Prevents acceptance for one use from becoming unrestricted permission.
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 5 bundles · 9 layers · 16 findings · 24 questions.
L-threonine identity Establish whether an observed material contains the registered stereochemical substance.
The name threonine and a matching molecular mass do not establish L-threonine identity.
Molecular connectivity
Assess evidence for the chemical structure represented by the registry entry.
Structure-supported identity
Record the identity conclusion together with the method, reference and sample to which it applies.
- What evidence establishes the amino, hydroxyl and carboxyl connectivity of the claimed L-threonine? definition
- Which sample and reference material support the identity result? provenance
Stereochemical discrimination
Separate an L-threonine assignment from unresolved threonine stereochemistry.
L-threonine stereoisomer evidence
Record which stereoisomers the method can distinguish and what uncertainty remains.
- Does the method distinguish L-threonine from D-threonine and allothreonine stereoisomers? measurement
- What unresolved stereoisomer contribution prevents an unqualified L-threonine assignment? boundary
Free threonine and content Determine what chemical form and quantity a reported threonine result represents.
Free L-threonine, hydrolysis-derived threonine and gross product mass support different decisions.
Free versus bound
Define the boundary between this substance and residues or derivatives.
Analytical form boundary
Record whether the result concerns free material or material released or transformed during preparation.
- Was threonine measured directly or after hydrolysis or another chemical transformation? provenance
- Does the specimen represent free L-threonine, a mixture component, a salt or a covalent derivative requiring a neighbouring model? boundary
Assay and impurities
Interpret L-threonine content against water, analytical selectivity and impurity evidence.
Usable L-threonine quantity
Retain enough measurement context to calculate content without overstating purity.
- What is the L-threonine mass fraction, on which water basis, and does the assay exclude other stereoisomers? measurement
- Which impurities were measured, with what reporting limits, and which required impurity checks remain missing? measurement
L-threonine material condition Assess the current solid or solution state and whether preparation or storage has changed usability.
An identity match alone cannot establish that a weighed portion or prepared solution delivers the intended amount.
Solid and solution state
Capture observations that govern sampling and solution preparation.
Preparation state evidence
Record water basis for solids and actual dissolution conditions for solutions.
- For a solid, what water measurement supports the mass used to calculate L-threonine content? measurement
- For a solution, what solvent, temperature, pH and concentration apply, and is dissolution complete? measurement
Storage and change
Link condition changes to evidence for retaining or reassessing the material.
Continued material suitability
Assess storage and post-preparation history without assuming a universal shelf life.
- What storage, opening and solution-preparation history applies to this L-threonine material? provenance
- Which observed changes or excursions require renewed assay, impurity testing or quarantine under the applicable specification? action
L-threonine use disposition Connect lot evidence and measured content to a specific proposed operation.
Suitability for analytical, formulation or other uses depends on evidence and requirements beyond the substance name.
Lot and specification
Determine whether the available evidence supports acceptance for the intended use.
Use-specific acceptance
Record an explicit disposition tied to a lot and a named set of requirements.
- Which lot-linked records support the claimed L-threonine identity, assay and grade? provenance
- Which requirements for the proposed use are met, failed or still unverified? action
Quantity and operation
Translate accepted material evidence into a controlled preparation or transfer.
Evidence-based preparation
Base the proposed operation on verified content, relevant handling information and an observable completion criterion.
- What mass or volume supplies the target L-threonine amount after accounting for assay, water basis and existing dilution? measurement
- What material-specific handling instructions and preparation checks must be satisfied before the portion or solution is released for use? action
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.
- Feed-grade L-threonine (fermentation, typically ≥98.5%)
- Pharmaceutical/USP-grade L-threonine
- Food/FCC-grade L-threonine
- Cell-culture / reagent-grade L-threonine
- L-Threonine hydrochloride / salts
- N-Acetyl-L-threonine and other protected derivatives
- Isotopically labelled L-threonine (e.g. 13C, 15N)
- L-Allothreonine (diastereomer, distinguished in stereochemistry work)
- Which of these kinds and varieties hold for the sense of L-threonine 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 - 72-19-5 - L-Threonine (not the racemate).
- PubChem CID - 6288 - L-Threonine.
- IUPAC InChIKey - AYFVYJQAPQTCCC-GBXIJSLDSA-N - Stereospecific key for (2S,3R)-threonine.
- EC / EINECS - 200-774-1 - L-Threonine.
- ChEBI - CHEBI:16857 - L-threonine.
- Wikidata - Q186521 - L-threonine item.
- UNII - 2ZD004190S - FDA Unique Ingredient Identifier.
- Which of these identifiers and schemes hold for the sense of L-threonine 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: Threonine
- FCC (Food Chemicals Codex) specification for L-Threonine
- JECFA / FAO-WHO specification for L-threonine as a food additive and nutrient
- EU feed additive authorisation of L-threonine produced by fermentation (Reg. (EC) No 1831/2003 framework)
- Codex / national pharmacopoeias (JP, Ph. Eur.) amino-acid monographs where listed
- GRAS / food-use notifications in the US for amino-acid nutrient supplementation
- Which of these standards and regulation hold for the sense of L-threonine 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.
- Essential amino-acid supplementation of cereal-based livestock and aquaculture feeds, especially swine and poultry, to meet threonine requirements after lysine.
- Parenteral and enteral nutrition formulas and amino-acid infusion solutions.
- Cell-culture media component for recombinant protein and vaccine production.
- Food and dietary-supplement ingredient (protein fortification, medical foods).
- Starting material or intermediate in peptide synthesis and specialty chemicals.
- Research reagent for metabolism, translation, and kinase (e.g. threonine phosphorylation) studies.
- Which of these real-world use hold for the sense of L-threonine 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.
- Assay (purity, dry basis) - 98.5-101.5 (pharm/feed grades often ≥98.5) - %
- Specific optical rotation [α]D20 (c=6, water) - −26 to −29 (L-form levorotatory in water under USP conditions) - °
- Melting / decomposition point - 255-257 (decomposes) - °C
- Aqueous solubility at 25 °C - about 90-100 - g/L
- Molecular mass - 119.12 - g/mol
- pKa (carboxyl / amino) - ~2.1 / ~9.1 - pKa units
- Dietary requirement (adult humans, WHO/FAO) - about 15 (mg/kg body weight/day; values vary by reference) - mg·kg⁻¹·d⁻¹
- Which of these typical measurements hold for the sense of L-threonine 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.
- Hygroscopic caking and microbial contamination of bulk powder if stored damp.
- Racemization or Maillard browning when heated with reducing sugars in feeds and foods.
- Over-supplementation in animal diets can unbalance the amino-acid profile and reduce performance.
- Inborn errors (e.g. threonine dehydratase / metabolism disorders) and rare hypersensitivity in medical nutrition.
- Dust explosion / inhalation nuisance in industrial handling of fine crystalline powder.
- Impurity risk: other amino acids, heavy metals, residual fermentation biomass or endotoxin in poorly purified lots.
- Which of these failure modes and hazards hold for the sense of L-threonine 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.
- Feed-grade L-threonine dominates production and trade in China, the EU, and North America; pharmaceutical grade is a smaller, more tightly specified stream.
- Labelling as 'threonine' vs 'L-threonine' vs E-number / INS 641 in food additive lists differs by jurisdiction.
- Japanese and European pharmacopoeial optical-rotation and impurity limits are not identical to USP.
- Some markets still quote DL-threonine historically, though commercial feed and food product is almost entirely the L-isomer from fermentation.
- Which of these regional variation hold for the sense of L-threonine 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-Threonine - Opposite configuration at both stereocentres; distinguished by specific rotation sign/magnitude and chiral HPLC or enzymatic L-amino-acid oxidase assays.
- L-Allothreonine - Diastereomer with (2S,3S) configuration; separated by chromatography and by melting point / NMR coupling of the β-proton.
- L-Serine - One-carbon shorter β-hydroxy amino acid (C3 vs C4); mass spectrometry (m/z 105 vs 119) or ninhydrin/HPLC amino-acid analysis.
- L-Homoserine - γ-hydroxy rather than β-hydroxy amino acid; different biosynthetic role (methionine/threonine pathway intermediate) and chromatographic retention.
- DL-Threonine (racemate) - Optical rotation near zero; CAS 80-68-2 vs 72-19-5 for the L-isomer.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of L-threonine this model covers, and on what evidence? provenance
Sources
- Threonine - Identity, formula, stereochemistry, identifiers, and physicochemical properties of L-threonine.
- L-Threonine (FAO/WHO food additive / amino acid specification) - Food-grade specification, assay, and impurity limits used in regulation.
What the second pass must settle
- Does an existing Vercy world model already own L-threonine, and how should this registry entry link to it?
- Which authoritative analytical methods establish L-threonine identity and resolve relevant stereoisomer impurities at the limits needed for each intended use?
- Which use-specific specifications govern assay basis, impurity limits and acceptance, and what evidence is required beyond a supplier grade label?
- What measured solubility and stability evidence applies across the actual solvents, pH values, temperatures and storage durations to be modelled?
- How should registry boundaries represent protonation states and separately supplied salts while preserving a single source of truth for L-threonine?