{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.homocitric-acid","code":"thing-q10860888","url":"https://ver.cy/models/thing/q10860888/","name":"homocitric acid","alternateNames":["(2S)-homocitric acid","homocitrate(3-)","(2R)-homocitric acid","(2R)-homocitrate(3-)"],"kind":"thing","status":"published","version":"0.1.0-research.1","language":"en","classifiers":{"family":"Thing Registry","category":"Physical world and living systems","entryKind":"thing","plane":"PHY","domain":["PHY.MAT"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"Homocitric acid is a seven-carbon hydroxytricarboxylic acid whose conjugate base, homocitrate, participates in the α-aminoadipate pathway of lysine biosynthesis and forms an organic ligand of the iron-molybdenum cofactor of nitrogenase.","purpose":"Enable an agent to recognise homocitric acid, assess the identity and condition of a particular sample, and determine its suitability for a specified analytical or biochemical use.","scope":{"in":["Molecular connectivity and identifiers qualified by stereochemical scope","Unspecified stereochemistry, identified enantiomers and measured enantiomer mixtures within the registered entry","Free-acid identity and its relationship to dissolved homocitrate species","Sample purity, concentration, water content and relevant impurities","Condition-dependent physical behaviour, stability and handling evidence","Suitability for analytical standards, enzyme studies and metal-binding investigations"],"out":["Independent substance models for homocitrate salts, esters and metal complexes","Complete lysine-biosynthesis pathways and their organism-specific regulation","Nitrogenase proteins and complete metal cofactors","Manufacturing processes and their equipment","Commercial formulations, packaging products and supplier organisations"],"boundaries":[]},"distinguishingFeatures":["Match the connectivity of 2-hydroxybutane-1,2,4-tricarboxylic acid, formula C7H10O7, rather than accepting a similar name; see [ChEBI homocitric acid](https://www.ebi.ac.uk/chebi/CHEBI:17852).","Require structural evidence for the hydroxyl and carboxyl positions when separating homocitric acid from possible constitutional isomers; formula or mass alone is insufficient.","Resolve whether stereochemistry is unspecified, experimentally assigned or a measured mixture; the parent entry includes distinct R and S forms and does not itself establish racemic composition. See [ChEBI homocitric acid](https://www.ebi.ac.uk/chebi/CHEBI:17852).","Distinguish the neutral free acid from charged homocitrate species, counterion-containing salts and coordinated ligands before transferring identifiers or sample masses.","Check the carbon skeleton explicitly when a label or assay could confuse homocitric acid with citric acid or another related organic acid."],"structure":{"bundles":[{"id":"identity-and-stereochemistry","name":"Identity and stereochemistry","description":"Establish which molecular structure and stereochemical specification a homocitric-acid record denotes.","layers":[{"id":"connectivity-and-identifiers","name":"Connectivity and identifiers","description":"Bind names and external identifiers to the intended chemical structure.","findings":[{"id":"parent-identity-match","name":"Parent identity match","description":"Record structure-backed identity and the precise scope of each database identifier.","questions":[{"text":"Does the proposed structure match 2-hydroxybutane-1,2,4-tricarboxylic acid rather than a related organic acid?","id":"parent-identity-match-q01","kind":"definition"},{"text":"Which verified CAS, PubChem, ChEBI and EC records describe the parent, a particular enantiomer or a mixture?","id":"parent-identity-match-q02","kind":"provenance"}]}]},{"id":"stereochemical-resolution","name":"Stereochemical resolution","description":"Separate structural specification from experimentally established enantiomer composition.","findings":[{"id":"enantiomer-assignment","name":"Enantiomer assignment","description":"Retain the assignment method and distinguish unknown composition from a demonstrated racemate.","questions":[{"text":"Is the material R, S, a quantified mixture or stereochemically unspecified, and what establishes that assignment?","id":"enantiomer-assignment-q01","kind":"measurement"},{"text":"Does the intended use require a particular enantiomer or an enantiomeric-purity threshold?","id":"enantiomer-assignment-q02","kind":"action"}]}]}]},{"id":"acid-base-state-and-material-form","name":"Acid-base state and material form","description":"Represent the relationship between nominal free acid, solution species and isolated material composition.","layers":[{"id":"solution-speciation","name":"Solution speciation","description":"Qualify acid-base descriptions by the actual solution conditions.","findings":[{"id":"protonation-evidence","name":"Protonation evidence","description":"Record measured or supported speciation without equating the reagent label with the dominant dissolved species.","questions":[{"text":"At the recorded pH, temperature and ionic strength, which protonation states are supported by evidence?","id":"protonation-evidence-q01","kind":"measurement"},{"text":"Which measured dissociation constants or validated equilibrium model support that assignment?","id":"protonation-evidence-q02","kind":"provenance"}]}]},{"id":"isolated-form-and-equivalents","name":"Isolated form and equivalents","description":"Determine what a weighed sample contains and how its amount relates to the free acid.","findings":[{"id":"material-basis","name":"Material basis","description":"Make water, solvent and counterion contributions explicit before calculating substance amounts.","questions":[{"text":"Does the supplied material contain free acid, a salt, water or residual solvent, and in what proportions?","id":"material-basis-q01","kind":"measurement"},{"text":"What verified composition and assay basis permit conversion of sample mass into homocitric-acid equivalents?","id":"material-basis-q02","kind":"action"}]}]}]},{"id":"analytical-quality-and-stability","name":"Analytical quality and stability","description":"Establish whether a batch contains the intended substance at a usable purity and retains that quality.","layers":[{"id":"identity-and-impurity-discrimination","name":"Identity and impurity discrimination","description":"Assess whether the analytical methods distinguish relevant alternatives.","findings":[{"id":"orthogonal-confirmation","name":"Orthogonal confirmation","description":"Combine structure-sensitive identity evidence with quantitative impurity and stereochemical assessments.","questions":[{"text":"Which NMR, chromatographic or other measurements distinguish homocitric acid from related or isomeric organic acids?","id":"orthogonal-confirmation-q01","kind":"measurement"},{"text":"Does the reported purity measure total chemical purity, enantiomeric purity or only detector-response area?","id":"orthogonal-confirmation-q02","kind":"boundary"}]}]},{"id":"physical-behaviour-and-retention","name":"Physical behaviour and retention","description":"Tie physical constants and quality retention to the tested material and conditions.","findings":[{"id":"condition-qualified-performance","name":"Condition-qualified performance","description":"Record solubility, thermal behaviour and storage observations with enough context to support preparation decisions.","questions":[{"text":"What solubility and thermal-event measurements exist for the specified stereochemical and material form, and was decomposition assessed?","id":"condition-qualified-performance-q01","kind":"measurement"},{"text":"Which storage conditions and retest interval are supported by measurements of identity, assay and impurity changes?","id":"condition-qualified-performance-q02","kind":"action"}]}]}]},{"id":"biochemical-and-metal-binding-fit","name":"Biochemical and metal-binding fit","description":"Assess the molecular-form requirements of proposed enzyme and coordination studies.","layers":[{"id":"enzyme-and-pathway-context","name":"Enzyme and pathway context","description":"Connect a proposed biochemical use to evidence for a particular organism and molecular form.","findings":[{"id":"biochemical-role-qualification","name":"Biochemical role qualification","description":"Require direct evidence before assigning a pathway role or treating one enantiomer as interchangeable with another.","questions":[{"text":"Which organism-specific experiments establish a homocitrate role in the proposed lysine-biosynthesis or other enzyme system?","id":"biochemical-role-qualification-q01","kind":"provenance"},{"text":"What stereochemistry, concentration, pH and impurity limits does that experiment require?","id":"biochemical-role-qualification-q02","kind":"action"}]}]},{"id":"coordination-context","name":"Coordination context","description":"Separate free material from metal-associated homocitrate in the system under study.","findings":[{"id":"ligand-versus-complex","name":"Ligand versus complex","description":"Record supported metal-binding relationships while keeping the resulting complex or cofactor outside the substance boundary.","questions":[{"text":"For the proposed metal-binding or nitrogenase-cofactor study, what evidence identifies the bound stereochemical form and coordination environment?","id":"ligand-versus-complex-q01","kind":"provenance"},{"text":"Is the measured behaviour attributable to free homocitrate, an equilibrium mixture or a separately identified metal complex?","id":"ligand-versus-complex-q02","kind":"boundary"}]}]}]},{"id":"handling-and-use-disposition","name":"Handling and use disposition","description":"Translate applicable substance evidence and batch measurements into handling and acceptance decisions.","layers":[{"id":"applicable-hazard-record","name":"Applicable hazard record","description":"Check that handling and regulatory evidence applies to the actual material.","findings":[{"id":"form-specific-handling-evidence","name":"Form-specific handling evidence","description":"Distinguish documented classification from missing data and from information about another acid or salt.","questions":[{"text":"Which current safety data sheet and jurisdictional records match this homocitric-acid form, composition and concentration?","id":"form-specific-handling-evidence-q01","kind":"provenance"},{"text":"What handling, incompatibility, disposal and exposure-control requirements are supported, and which remain unassessed?","id":"form-specific-handling-evidence-q02","kind":"action"}]}]},{"id":"batch-release-for-purpose","name":"Batch release for purpose","description":"Judge a specific batch against the requirements of its intended analytical or biochemical use.","findings":[{"id":"fitness-decision","name":"Fitness decision","description":"Make acceptance contingent on verified identity, appropriate stereochemistry, quantity basis and retained quality.","questions":[{"text":"Does this batch meet the intended use's identity, enantiomer composition, assay and interference limits?","id":"fitness-decision-q01","kind":"action"},{"text":"Which missing or failed checks require additional analysis, quarantine or rejection before use?","id":"fitness-decision-q02","kind":"action"}]}]}]},{"id":"evidence-and-external-alignment","name":"Evidence and external alignment","description":"What the world already says about this thing, gathered so the model can be checked against it.","layers":[{"id":"reported-evidence","name":"Reported evidence","description":"Findings from the breadth pass, kept separate from the structural claims.","findings":[{"id":"evidence-confidence-notes","name":"Check these first","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these check these first hold for the sense of homocitric acid this model covers, and on what evidence?","id":"evidence-confidence-notes-q01","kind":"provenance"}]},{"id":"evidence-kinds","name":"Kinds and varieties","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these kinds and varieties hold for the sense of homocitric acid this model covers, and on what evidence?","id":"evidence-kinds-q01","kind":"provenance"}]},{"id":"evidence-identifiers","name":"Identifiers and schemes","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these identifiers and schemes hold for the sense of homocitric acid this model covers, and on what evidence?","id":"evidence-identifiers-q01","kind":"provenance"}]},{"id":"evidence-real-world-use","name":"Real-world use","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these real-world use hold for the sense of homocitric acid this model covers, and on what evidence?","id":"evidence-real-world-use-q01","kind":"provenance"}]},{"id":"evidence-measurements","name":"Typical measurements","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these typical measurements hold for the sense of homocitric acid this model covers, and on what evidence?","id":"evidence-measurements-q01","kind":"provenance"}]},{"id":"evidence-neighbours","name":"Neighbouring kinds and how to tell them apart","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these neighbouring kinds and how to tell them apart hold for the sense of homocitric acid this model covers, and on what evidence?","id":"evidence-neighbours-q01","kind":"provenance"}]}]}]}]},"agentConduct":{"may":["Describe homocitric acid and its role in lysine synthesis and nitrogenase, citing biochemistry sources.","Look up its identifiers and properties in chemical databases."],"mustNot":["Confuse it with citric acid or other similar acids in records or orders.","Present research findings on nitrogenase as settled when they are disputed.","Handle laboratory samples outside the lab's safety rules.","Invent properties or data."],"requiresHuman":["Ordering or handling laboratory chemicals."]},"ethics":{"considerations":["Accurate science depends on not overstating results.","Credit belongs to the researchers who made the findings."],"affectedParties":["Researchers","Students"]},"owners":{"steward":"Nobody owns the compound; laboratories answer for the samples they hold.","roles":[],"masterSystems":["Chemical substance databases"]},"relations":[{"target":"Q11173","type":"parent","note":"registry parent class"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.homocitric-acid","Wikidata: Q10860888 (https://www.wikidata.org/wiki/Q10860888)"]},"properties":{"applicability":"required","items":["Molecular identity: Structure representation and identifier set; parent formula C7H10O7","Stereochemical specification: R; S; measured mixture; unspecified, with assignment evidence","Enantiomeric composition: Mole fraction of each enantiomer or enantiomeric excess in %, with method","Acid-base and coordination state: Free acid; specified ionisation state; unresolved equilibrium mixture; metal-associated, with pH and medium","Assay and impurity profile: Mass % or mol %, with as-received or dry basis, method and identified impurities","Water and counterion content: Water mass %; counterion identity and molar ratio","Solution concentration: mol/L or g/L, with analyte basis, solvent, pH and temperature","Physical behaviour: Solubility in g/L or mol/L; thermal events in °C, each with conditions and method","Biochemical context: Linked enzyme, pathway or cofactor study, with organism and stereochemical requirements","Handling evidence status: Applicable current evidence; conflicting evidence; insufficient evidence, qualified by material form and jurisdiction"]},"recognition":{"applicability":"required","items":["A sample label naming homocitric acid distinguishes the intended contents from similarly named organic acids.","A label specifying stereochemistry distinguishes a defined stereoisomer from material with unspecified stereochemistry.","The container description should distinguish the free acid from a homocitrate salt, although appearance alone cannot verify either identity."]},"capabilities":{"applicability":"required","items":["Resolve a labelled sample to the registered parent substance while preserving stereochemical and salt-form distinctions.","Select identity and purity measurements that discriminate related organic acids and enantiomers.","Calculate free-acid-equivalent quantities from verified assay, water and counterion information.","Assess a solution preparation against measured solubility, pH and stability constraints.","Determine whether a batch meets the molecular-form and purity requirements of a specified biochemical experiment.","Accept, quarantine or reject a sample against documented identity, quality and handling criteria."]},"hazards":{"applicability":"required","items":["Confusion with citric acid, a homocitrate salt or a different stereoisomer can invalidate biochemical or analytical results.","Contamination or an incorrectly characterised sample can distort measurements and compromise experimental conclusions.","Uncharacterised exposure can present health risks that require assessment from the preparation-specific safety information."]},"interfaces":{"applicability":"required","items":["The Globally Harmonized System of Classification and Labelling of Chemicals, issued by the United Nations, provides the framework for assessing and communicating chemical hazards without establishing a substance-specific classification."]},"context":{"applicability":"required","items":["This organic acid is encountered in biochemical research on lysine biosynthesis and nitrogen fixation.","Characterised samples support analytical comparisons and investigations of homocitrate as a component of enzyme-associated metal cofactors."]}},"sources":[{"title":"Wikidata item Q10860888: homocitric acid","url":"https://www.wikidata.org/wiki/Q10860888","note":"identity and sense of the item"},{"title":"Wikipedia: Homocitric acid","url":"https://en.wikipedia.org/wiki/Homocitric_acid","note":"general description of the item"}],"openQuestions":["Does the originating registry record intend stereochemically unspecified homocitric acid, a racemate or a particular enantiomer, and how should external identifier conflicts be resolved?","Which reliable measurements establish dissociation constants, solubility and thermal behaviour for each relevant material form under explicit conditions?","What degradation products and storage limits have been experimentally established for the free acid and its prepared solutions?","Which primary studies establish the stereochemical and coordination requirements of the proposed lysine-pathway and nitrogenase-related uses?","Which applicable hazard classifications, EC identifiers and exposure limits are documented, and where is the evidence simply absent?"],"resources":{"spec":"/models/things/publications/thing-q10860888/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q10860888/spec.json"],"providers":["Codex"],"researchStatus":"unreviewed","generatedAt":"2026-09-12T10:18:30Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"filled","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-07T10:10:25+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass"},"score":1.0}}