L-isoleucine
Enable an AI agent to recognise L-isoleucine, assess the identity and condition of material containing it, and decide whether that material 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-isoleucine, assess the identity and condition of material containing it, and decide whether that material is suitable for a specified use.
L-Isoleucine is the (2S,3S)-2-amino-3-methylpentanoic acid enantiomer of the branched-chain amino acid isoleucine, an essential proteinogenic residue encoded by AUU, AUC and AUA, distinguished from its allo and D stereoisomers by the (S) configuration at both C2 and C3.
It can be Identify material as L-isoleucine or flag unresolved structural and stereochemical alternatives.; Calculate a required material quantity from measured L-isoleucine content and its stated basis.; Prepare a solution under recorded conditions and verify its concentration and dissolution state.; Select complementary identity, stereoisomer and impurity measurements for a proposed use.; Accept, quarantine or request retesting of a lot against an applicable specification.; Link L-isoleucine consumption or incorporation to a reaction, culture or formulation record..
Distinguishing features
Require connectivity matching 2-amino-3-methylpentanoic acid and configuration (2S,3S), rather than accepting an unspecified isoleucine label. [ChEBI](https://www.ebi.ac.uk/chebi/CHEBI%3A17191)
Use structural or validated separation evidence to distinguish leucine and other constitutional isomers; molecular formula or mass alone does not establish L-isoleucine identity.
Require a method capable of resolving relevant stereoisomers before distinguishing L-isoleucine from D-isoleucine or alloisoleucine; an achiral identity assay alone is insufficient.
Determine whether the measurement represents free L-isoleucine or material released from peptides and proteins during sample preparation.
Distinguish a change in protonation from a change in covalent identity: the zwitterion retains L-isoleucine identity while expressing charged amino and carboxyl groups. [ChEBI zwitterion record](https://www.ebi.ac.uk/chebi/searchId.do?chebiId=58045)
Scope
+ L-isoleucine molecular connectivity and stereochemical identity
+ Free amino acid and its condition-dependent protonation states
+ Identification and quantification in isolated material or a specified matrix
+ Chemical purity, stereoisomer composition and relevant contamination
+ Material condition, preparation history and suitability for a declared application
- Leucine, valine and other amino acids as independently modelled substances
- D-isoleucine and alloisoleucine as independently modelled stereoisomers
- Peptides, proteins and covalently modified isoleucine derivatives
- Complete formulations, foods and culture media containing L-isoleucine
- Patient diagnosis, dietary requirements and treatment decisions
- Manufacturing equipment and complete fermentation or synthesis processes
Characteristics
- Identity evidence
- Assigned structure linked to reference material, analytical result and method A supplier name or shared molecular formula cannot resolve structural and stereochemical alternatives.
- Stereochemical composition
- Mole fraction or percentage of individually resolved isoleucine stereoisomers; unresolved fraction stated Chemical assay and stereochemical purity answer different questions about the material.
- Chemical presentation
- Isolated free amino acid, solution, mixture component or separately identified salt presentation Presentation determines which mass basis, counterions and preparation conditions must accompany an assessment.
- Solution conditions
- pH, temperature in °C, solvent composition and ionic strength where relevant Protonation, dissolution and analytical behaviour must be interpreted under recorded conditions.
- L-isoleucine content
- mg, mmol, mg/mL, mmol/L or mass percentage, with explicit sample and moisture basis Supports preparation and comparison without confusing material mass with actual L-isoleucine amount.
- Water and volatile content
- Mass percentage with method; water distinguished from total loss on drying Moisture and residual volatiles can alter the relationship between weighed mass and amino acid content.
- Application-relevant impurities
- Identity and concentration of specified impurities, with detection and quantification limits Other amino acids, process residues and contamination can invalidate a use even when identity is confirmed.
- Material condition
- Documented appearance, dissolution state, exposure history and retest status Condition changes determine whether earlier analytical evidence still supports use.
- Intended-use qualification
- Material linked to application, specification version, supporting evidence and disposition Suitability as a reference standard, culture ingredient or formulation input cannot be inferred from chemical identity alone.
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 · 18 findings · 32 questions.
Molecular and stereochemical identity Evidence that the recorded substance has L-isoleucine connectivity and stereochemistry.
Closely related amino acids and isoleucine stereoisomers can satisfy incomplete identity checks.
Connectivity recognition
Establish the amino acid skeleton independently of naming conventions.
Isoleucine connectivity
Record evidence supporting the assigned connectivity and excluding relevant constitutional isomers.
- What structural evidence establishes 2-amino-3-methylpentanoic acid rather than leucine or another isomer? definition
- Which reference material and analytical method support the identity assignment? provenance
Stereochemical recognition
Resolve both stereocentres and identify limits of the available evidence.
Two-centre configuration
Require explicit support for the L-isoleucine configuration and separately account for unresolved stereoisomers.
- What evidence establishes the (2S,3S) assignment at both stereocentres? measurement
- Does the method distinguish D-isoleucine and the relevant alloisoleucine stereoisomers at the required limits? boundary
Chemical form and dissolution The form in which L-isoleucine is present and the conditions governing its preparation.
A free amino acid, its solution species and a salt presentation require different accounting and preparation evidence.
Protonation and presentation
Distinguish reversible solution speciation from separately constituted material.
Form assignment
Record the material presentation, counterions where present and conditions supporting any protonation assignment.
- Is the material an isolated free amino acid, a solution species or a salt with an identified counterion? definition
- What measured pH and solvent conditions support the assigned protonation state? measurement
- Does the presentation require a linked salt or mixture model while retaining L-isoleucine as the component identity? boundary
Dissolution and preparation
Establish whether the required amount is dissolved under the actual preparation conditions.
Verified solution state
Record solvent, temperature, pH adjustment and evidence of complete dissolution or precipitation.
- At the intended concentration, solvent composition, pH and temperature, is the L-isoleucine fully dissolved? measurement
- What preparation or concentration adjustment is supported if undissolved material or later precipitation is observed? action
Content and analytical selectivity Quantification of L-isoleucine with explicit analyte boundaries, sample basis and method limitations.
A reported amino acid concentration may combine isomers, include hydrolysis products or use an incompatible mass basis.
Analyte boundary
Define what the measurement actually counts as L-isoleucine.
Free versus released content
Separate free L-isoleucine measurements from results obtained after cleavage of peptide-bound material.
- Does the result quantify free L-isoleucine, hydrolytically released isoleucine or an unresolved combined signal? definition
- What extraction, hydrolysis or derivatisation steps could change recovery or stereochemical interpretation? provenance
Quantitative confidence
Relate the measured amount to selective detection and a defensible calculation basis.
Selective content result
Record calibration, interference checks, uncertainty and the mass or volume basis of the result.
- How does the method exclude contributions from leucine, other stereoisomers and matrix interference? measurement
- Is content reported as received, on a dry basis or as free-amino-acid equivalent, and what corrections were applied? measurement
- What amount of this material supplies the requested L-isoleucine quantity within the required uncertainty? action
Lot purity and condition Evidence that a particular L-isoleucine lot remains sufficiently pure and fit for evaluation.
Confirmed molecular identity does not establish lot quality or the continuing validity of a certificate.
Impurity and origin evidence
Connect lot origin to relevant impurity measurements.
Route-relevant purity
Record origin and purification evidence to justify which related amino acids, residues and contaminants require assessment.
- What production and purification history is documented for this L-isoleucine lot? provenance
- Which related amino acids, stereoisomers, process residues or contaminants were measured, and with what limits? measurement
Condition and retest
Assess whether storage and preparation history leave the analytical qualification applicable.
Continued lot validity
Connect moisture, appearance, exposure and solution history to evidence-based retest decisions.
- Have water content, appearance, dissolution behaviour or assay changed relative to the qualified lot? measurement
- Which documented storage or preparation limits were exceeded, and what evidence supports retesting or continued use? action
Application fit and disposition Translate L-isoleucine identity and material evidence into a decision for a declared application.
Requirements for an analytical reference, culture nutrient or formulation ingredient differ even for the same chemical identity.
Role-specific qualification
Connect the intended role to the necessary analytical and quality evidence.
Declared use requirements
Record the proposed role and its acceptance requirements without inferring suitability from a grade label.
- Will the L-isoleucine serve as an analytical reference, reaction substrate, culture ingredient or formulation input? definition
- Which application-specific requirements for assay, stereoisomers, impurities and contamination apply? boundary
- Which specification and lot-specific evidence substantiate the claimed grade? provenance
Use decision
Determine the supported material action and its boundary with the receiving process or product.
Supported disposition
Record whether available evidence supports use, restricted use, quarantine or further testing.
- Do the measured identity, content, impurity profile and condition support the intended use, or is further testing required? action
- Which handling and preparation instructions are supported by the lot documentation and receiving process? action
- At what point must a decision be transferred to a formulation, biological system or clinical 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 L-isoleucine (crystalline amino-acid ingredient)
- Protein-bound L-isoleucine residues in peptides and proteins
- Pharmaceutical-grade L-isoleucine (USP/Ph. Eur. monograph substance)
- Feed-grade L-isoleucine (amino-acid supplement for livestock diets)
- Food-grade L-isoleucine (flavour enhancer / dietary-supplement ingredient)
- Isotopically labelled L-isoleucine (13C, 15N, or deuterated research reagents)
- L-isoleucine salts and esters (e.g. hydrochloride, ethyl ester)
- Cell-culture media L-isoleucine (sterile, endotoxin-controlled)
- Which of these kinds and varieties hold for the sense of L-isoleucine 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 - 73-32-5 - L-isoleucine specifically; racemic isoleucine is 443-79-8; D-isoleucine is 319-78-8.
- PubChem CID - 6306 - L-isoleucine; allo-L-isoleucine is CID 99288.
- ChEBI - CHEBI:17191 - L-isoleucine.
- IUPAC InChIKey - AGPKZVBTJJNPAG-WHFBIAKZSA-N - Stereospecific; the InChI encodes (2S,3S).
- Wikidata - Q484940 - item L-isoleucine.
- EC / EINECS - 200-798-2 - European inventory number for L-isoleucine.
- UNII - 04S9037O6P - FDA Unique Ingredient Identifier.
- IUPAC / three-letter / one-letter codes - L-isoleucine / Ile / I - Protein sequence notation; codon set AUU, AUC, AUA.
- Which of these identifiers and schemes hold for the sense of L-isoleucine 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.
- United States Pharmacopeia (USP) monograph Isoleucine - identity, assay, specific rotation, related substances.
- European Pharmacopoeia (Ph. Eur.) monograph Isoleucine (01/2008:0770) - same class of tests as USP.
- Japanese Pharmacopoeia (JP) Isoleucine - JP-grade pharmaceutical substance.
- WHO Technical Report Series 970 Annex 3 specifications for isoleucine (pharmaceutical quality).
- Commission Regulation (EU) No 1831/2003 and related EFSA opinions - L-isoleucine as a feed additive (functional group: amino acids, their salts and analogues).
- FDA 21 CFR (food additive / GRAS pathway for amino acids used in food and dietary supplements; isoleucine listed among amino acids used in food).
- Codex Alimentarius / FAO-WHO amino-acid scoring (IAAO / DIAAS frameworks treat isoleucine as an indispensable amino acid with a scoring pattern).
- FCC (Food Chemicals Codex) specification for L-isoleucine as a food ingredient.
- Which of these standards and regulation hold for the sense of L-isoleucine 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 residue in dietary protein; humans cannot synthesise it and must obtain it from food or supplements.
- Crystalline feed additive, typically produced by fermentation (E. coli or Corynebacterium), blended into swine, poultry and aquaculture diets to meet ileal digestible isoleucine requirements without overfeeding intact protein.
- Component of parenteral nutrition amino-acid solutions and of medical foods for maple-syrup-urine-disease (MSUD) management, where isoleucine intake is tightly titrated.
- Ingredient in sports-nutrition BCAA powders (leucine : isoleucine : valine blends, commonly 2:1:1).
- Cell-culture media component; mammalian cells require exogenous L-isoleucine.
- Starting material or chiral building block in peptide synthesis and some small-molecule APIs.
- Flavour / savoury note in some processed foods (bitter-sweet branched-chain amino acid taste).
- Which of these real-world use hold for the sense of L-isoleucine 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.
- Molecular mass - 131.17 (monoisotopic 131.0946) - g mol−1
- Specific optical rotation [α]D20 (c = 4 in 6 M HCl, Ph. Eur./WHO) - +38.0 to +42.0 (often about +40) - ° (degrees)
- Aqueous solubility (25 °C) - about 30-40 (sparingly to freely soluble depending on pH) - g L−1
- Isoelectric point (pI) - about 6.0 - pH units
- Melting / decomposition point - about 284-288 (decomposes) - °C
- Assay (dried basis, pharmacopoeial) - 98.5-101.5 - %
- Human adult estimated average requirement (WHO/FAO/UNU 2007 scoring pattern, isoleucine) - 20 (mg per g protein) or about 20 mg kg−1 d−1 depending on the reference used - mg g−1 protein or mg kg−1 d−1
- Plasma concentration (healthy fasting adult) - about 40-100 - µmol L−1
- Which of these typical measurements hold for the sense of L-isoleucine 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.
- Maple syrup urine disease (branched-chain α-ketoacid dehydrogenase deficiency): accumulation of isoleucine, leucine and valine and their keto-acids; isoleucine excess contributes to metabolic decompensation.
- Dietary imbalance of branched-chain amino acids: excess leucine can antagonise isoleucine (and valine) utilisation; low dietary isoleucine relative to leucine causes reduced feed intake in pigs and poultry.
- MSUD medical-food error: too little isoleucine in a restricted diet produces an isoleucine-deficiency rash (acrodermatitis-like eruption) and growth failure; too much precipitates ketoacidosis.
- Stereochemical contamination: allo-isoleucine and D-isoleucine fail pharmacopoeial specific-rotation and related-substance tests and are metabolically non-equivalent.
- Fermentation-process impurities (endotoxin, residual host DNA/protein, other amino acids) if the feed- or pharma-grade purification is incomplete.
- Hygroscopicity and Maillard browning when stored with reducing sugars at elevated temperature/humidity, degrading assay and generating off-colours.
- Not an acute toxicant at food-use levels; very high supplemental BCAA intakes can raise plasma ammonia and compete with other large-neutral amino acids at the blood-brain barrier.
- Which of these failure modes and hazards hold for the sense of L-isoleucine 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.
- English and most pharmacopoeias use "isoleucine" / "L-isoleucine"; Japanese JP uses イソロイシン (isoroi shin).
- Feed-grade crystalline L-isoleucine is widely used in East-Asian and European pig and poultry formulation; uptake in North-American commercial diets is later and more leucine-driven.
- MSUD newborn-screening cut-offs and whether allo-isoleucine is the primary marker vary by programme (US state labs vs many EU programmes).
- Food-additive listing: EU treats crystalline L-isoleucine primarily as a feed additive and as a food-supplement amino acid; US lists amino acids including isoleucine under food-additive / GRAS and USP dietary-ingredient frameworks rather than an E-number.
- Which of these regional variation hold for the sense of L-isoleucine 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-isoleucine - Opposite configuration at both stereocentres (2R,3R). Separated by specific optical rotation (L is strongly dextrorotatory in HCl; D is levorotatory) and by chiral HPLC or GC of derivatives.
- L-allo-isoleucine (2S,3R) - Epimer at C3; diagnostic plasma marker of MSUD. Separated from L-isoleucine by ion-exchange or reversed-phase HPLC of amino-acid derivatives, and by 13C NMR / optical rotation.
- D-allo-isoleucine (2R,3S) - The remaining diastereomer of 2-amino-3-methylpentanoic acid. Same chromatographic and polarimetric tests as for the other three stereoisomers.
- L-leucine - Isomeric branched-chain amino acid (2-amino-4-methylpentanoic acid, one stereocentre). Distinguished by ninhydrin/ion-exchange elution order, mass spectrometry of isobaric fragments after derivatisation, and by side-chain NMR (isoleucine has a sec-butyl chain with a chiral β-carbon).
- L-valine - Smaller branched-chain amino acid (2-amino-3-methylbutanoic acid). Separated by amino-acid analysis (shorter retention than Ile) and by molecular mass (117 vs 131).
- Norleucine (2-aminohexanoic acid) - Straight-chain isomer sometimes used as an internal standard; co-elutes with isoleucine in some ninhydrin systems. Distinguised by HPLC method selection or by MS (same C6H13NO2 formula - needs chromatography, not mass alone).
- Which of these neighbouring kinds and how to tell them apart hold for the sense of L-isoleucine this model covers, and on what evidence? provenance
Sources
- Isoleucine, Compound Summary CID 6306 - Canonical identity, formula, stereochemistry, CAS, InChI, melting point, solubility, and encoded-codon facts.
- WHO Technical Report Series 970, Annex 3: Specifications for isoleucine - Pharmacopoeial identity tests, assay, specific rotation, and impurity limits used as a pharmaceutical substance.
- Scientific Opinion on the safety and efficacy of L-isoleucine produced by Escherichia coli FERM ABP-10641 for all animal species - Feed-additive use, typical dietary inclusion, manufacturing organism, and EU regulatory framing.
- Isoleucine (Ile, I) - IUPAC recommended name and proteinogenic-amino-acid status.
What the second pass must settle
- Does an existing Vercy world model already own L-isoleucine, and what registry conventions govern links to its salts, protonation states and stereoisomers?
- Which reference methods and materials adequately resolve L-isoleucine from leucine and all relevant isoleucine stereoisomers in the intended matrices?
- Which authoritative specifications and impurity limits apply to each intended grade, application and jurisdiction?
- What measured solubility and stability evidence supports the intended solvent, pH, temperature, concentration and storage conditions?
- How should results after hydrolysis or derivatisation be qualified when recovery and stereochemical preservation have not been established?