purine
Enable an AI agent to recognise parent purine, assess the identity and condition of a purine-containing material, and determine which handling, analytical or chemical actions are justified by available evidence.
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 parent purine, assess the identity and condition of a purine-containing material, and determine which handling, analytical or chemical actions are justified by available evidence.
Purine is the fused pyrimidine-imidazole heterocycle that is the parent scaffold of the nucleobases adenine and guanine and of their nucleosides, nucleotides, and catabolites.
It can be Resolve whether a record denotes parent purine, a derivative or a collective purines measurement.; Select an analytical comparison that can test parent purine identity against plausible alternatives.; Calculate a usable quantity from measured parent purine content and its reporting basis.; Evaluate dissolution or changes in chemical conditions using evidence applicable to the actual material.; Assess a proposed chemical transformation and link resulting derivatives to their own identities.; Approve, condition or defer handling and use according to material-specific evidence and the intended operation..
Distinguishing features
The assigned structure must have the fused six-membered and five-membered ring connectivity of purine, including its four ring nitrogen positions; a formula match alone is insufficient.
Neutral parent purine has molecular formula C5H4N4; additional amino, oxo, methyl or other substituents identify derivatives rather than the parent entity.
A single six-membered nitrogen heterocycle is insufficient: pyrimidine lacks purine's fused five-membered ring.
A covalently attached sugar or sugar-phosphate component identifies a nucleoside or nucleotide rather than free parent purine.
A result reported as 'total purines' does not establish the presence or amount of parent purine without a method that distinguishes the relevant compounds.
Scope
+ Identity of the parent purine ring system and molecular composition
+ Evidence that a material contains parent purine rather than only purine derivatives
+ Tautomeric, protonation and physical states under recorded conditions
+ Purine content, impurities and changes in a specimen
+ Purine-specific analytical, transformation and handling decisions
- Independent models of substituted purines such as adenine and guanine
- Nucleosides, nucleotides and nucleic acids containing purine-derived bases
- Purine biosynthesis, salvage and degradation pathways as biological systems
- Clinical interpretation of dietary purines, uric acid or gout
- Full equipment, container and laboratory procedure models
Characteristics
- Chemical referent
- parent purine | purine derivative | collective purines | unresolved Prevents family-level labels and biological measurements from being treated as evidence about the parent compound.
- Structural identity evidence
- assigned molecular structure linked to analytical observations, reference material or documented supplier identity Supports recognition through connectivity and composition rather than an ambiguous name.
- Protonation and tautomer assignment
- assigned form or unresolved mixture, with method, solvent, pH where applicable and temperature Hydrogen placement and charge affect interpretation of spectra, interactions and chemical behaviour.
- Physical presentation
- solid | dissolved | suspension | other documented phase; solid form assigned or unresolved Determines whether sampling, dissolution or solid-state characterisation is needed before use.
- Parent purine content
- mol/L for solutions, or mass fraction or mole fraction with explicit basis and uncertainty Makes quantities usable while avoiding confusion with total purines or uncalibrated analytical response.
- Associated chemical species
- identified derivatives, counterions, solvents, water and impurities, with quantities where established Distinguishes the purine entity from the complete composition of the material being assessed.
- Condition history
- dated exposure and analytical records linked to a specimen or batch Allows an agent to judge whether earlier identity and content measurements still support the proposed use.
- Fitness for intended use
- supported | conditional | unsupported | unassessed, against stated acceptance criteria Connects identity, composition and condition evidence to a specific analytical or chemical action.
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 · 31 questions.
Parent purine identity Establishes what the name purine denotes and whether the chemical evidence supports that interpretation.
Purine can denote a particular parent compound or appear in language referring to a broad chemical family.
Referent boundary
Separates the parent compound from derivatives and collective measurements.
Parent or family
Record the intended referent and the evidence that resolves ambiguous use of the name.
- Does this record mean parent purine, a named derivative or a collection reported as purines? definition
- Which original label, structure or analytical report establishes that interpretation? provenance
Molecular recognition
Tests the parent ring connectivity and absence of derivative-defining substitutions.
Parent structure evidence
Record evidence for the purine skeleton and distinguish a supported assignment from a name or formula match.
- What evidence supports the fused ring connectivity and nitrogen positions of parent purine? measurement
- Does the assigned structure contain an added substituent or covalently attached sugar that places it outside parent purine? boundary
Purine material composition Connects the chemical identity to the composition and measured content of a particular material.
A purine-labelled specimen may contain solvents, impurities or derivatives that change what its measured quantity means.
Specimen assignment
Connects identity evidence to the actual batch, aliquot or preparation being used.
Identity evidence transfer
Record how the material under consideration is linked to the purine identity evidence.
- Which batch or aliquot was examined to establish parent purine identity? provenance
- What preparation or mixing steps occurred between that examination and the material now proposed for use? provenance
Content and co-components
Distinguishes parent purine quantity from total material mass and other analytical signals.
Specific purine assay
Record parent purine content with its measurement basis and relevant chemical interferences.
- What parent purine content was measured, on what basis and with what uncertainty? measurement
- Which derivatives or other components could contribute to the reported signal, and how were they distinguished? measurement
- Does the reported purity describe parent purine mass fraction, chromatographic area fraction or another explicitly defined quantity? definition
Purine form and environment Records the chemical and physical forms relevant to interpreting or using purine under specified conditions.
A parent identity alone does not settle charge, hydrogen placement, dissolution state or solid form.
Protonation and tautomerism
Tracks supported assignments of charge and mobile hydrogen positions without assuming one form applies universally.
Condition-dependent form
Record any assigned protonation or tautomeric state together with the conditions and evidence supporting it.
- Which protonation or tautomeric form is supported, or is the assignment unresolved? definition
- Under which solvent, temperature and acid-base conditions was that assignment established? measurement
- Is that assignment applicable under the conditions of the proposed action? action
Phase and dissolution
Establishes whether purine is present in a solid phase, solution or a mixture of phases.
Available purine phase
Record the observed physical presentation and whether the intended quantity is actually dissolved or otherwise accessible.
- Is the purine fully dissolved, suspended or present as a characterised or uncharacterised solid? measurement
- What evidence under the intended solvent, temperature and concentration supports complete dissolution or predicts precipitation? action
Purine change and products Distinguishes changes in form from chemical conversion and tracks the evidence for resulting identities.
An agent must know when a material still represents parent purine and when a transformation has produced another chemical entity.
Condition change
Assesses whether exposure or storage has changed parent purine content or introduced additional species.
Retained parent identity
Record observed change relative to an earlier characterisation without presuming a degradation mechanism.
- Do measurements after storage or exposure still support the earlier parent purine identity and content? measurement
- Which recorded exposures are relevant to investigating any newly observed species or loss of parent purine? provenance
Chemical conversion
Connects proposed reactions and observed products to the boundary of the parent purine model.
Transformation and identity boundary
Record the intended structural change, supporting reaction evidence and the resulting chemical identity.
- Which atom or bond change is intended, and what evidence supports that transformation for parent purine under the proposed conditions? action
- Does the observed change represent protonation or tautomerism, or does it produce a distinct derivative or decomposition product? boundary
- What analysis distinguishes remaining parent purine from the proposed products? measurement
Purine use decisions Connects the actual purine material and proposed operation to evidence-based acceptance and handling decisions.
Neither a family-level biological association nor an unverified parent-compound label is enough to justify a laboratory action.
Fitness for operation
Assesses whether the material meets the requirements of a particular use as parent purine.
Operation-specific acceptance
Record the required identity confidence, content and impurity limits for the intended operation.
- Does the intended operation require parent purine specifically, and what identity, content and impurity criteria apply? action
- Which available measurements satisfy those criteria, and which unresolved issue requires further analysis before use? action
Handling evidence
Matches handling information to parent purine in the actual formulation and operation.
Applicable handling basis
Record an applicable handling basis without transferring claims from dietary purines or unrelated derivatives.
- Which safety and compatibility information explicitly applies to parent purine and this material's formulation? provenance
- Given its physical form, co-components and proposed operation, which handling and disposal measures are supported by that information? 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.
- parent heterocycle (purine, C5H4N4)
- nucleobases (adenine, guanine, hypoxanthine, xanthine)
- nucleosides (adenosine, guanosine, inosine)
- nucleotides and cofactors (AMP, ATP, GTP, NAD, FAD, coenzyme A)
- uric acid and urate (human end-product of purine catabolism)
- methylxanthine alkaloids (caffeine, theophylline, theobromine)
- dietary purines in food
- synthetic purine analogues used as drugs (e.g. 6-mercaptopurine, allopurinol, aciclovir)
- Which of these kinds and varieties hold for the sense of purine 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 - 120-73-0 - Parent heterocycle purine.
- PubChem CID - 1044 - Parent compound record.
- ChEBI - CHEBI:17258 - Preferred 7H/9H tautomer class for the parent.
- Wikidata - Q47477 - Item for the chemical compound purine.
- InChIKey - KDCGOANMDULRCW-UHFFFAOYSA-N - Standard InChIKey for unsubstituted purine.
- UNII - W97O5H3Wmk - FDA Unique Ingredient Identifier; confirm case in FDA SRS.
- Which of these identifiers and schemes hold for the sense of purine 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.
- IUPAC recommendations on fused heterocyclic nomenclature (purine numbering, 7H/9H tautomerism).
- Pharmacopoeial monographs for individual purine drugs and methylxanthines (USP, Ph. Eur., JP) rather than for the parent heterocycle.
- Clinical practice guidelines on hyperuricaemia and gout that treat dietary purine load and serum urate as managed quantities (ACR, EULAR).
- Which of these standards and regulation hold for the sense of purine 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.
- DNA and RNA nucleobases adenine and guanine, and the corresponding nucleosides and nucleotides.
- Cellular energy and signalling cofactors (ATP, GTP, cAMP, NAD, FAD).
- Dietary constituents whose intake is managed in gout and urate-kidney-stone care.
- Plant alkaloids in coffee, tea, cocoa, and related drugs (caffeine, theophylline, theobromine).
- Antimetabolite, antiviral, and urate-lowering medicines built on the purine scaffold.
- Which of these real-world use hold for the sense of purine 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 of parent purine - 120.11 - g mol−1
- melting point of parent purine - 214-217 - °C
- dietary purine content of foods - about 10-400 (much higher in some organ meats and some seafood) - mg per 100 g edible portion
- serum urate (clinical proxy of purine end-product in humans) - about 200-420 in adults, with laboratory- and sex-specific reference intervals - µmol L−1
- Which of these typical measurements hold for the sense of purine 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.
- Excess net purine load or underexcretion of urate causing hyperuricaemia, gouty arthritis, and urate nephrolithiasis.
- Tumour lysis releasing nucleic-acid purines and precipitating acute uric-acid nephropathy.
- Cytotoxicity of some purine antimetabolites (bone-marrow suppression, immunosuppression).
- Acute methylxanthine toxicity (caffeine, theophylline) at high dose.
- The parent heterocycle itself is not a bulk industrial hazard in ordinary use.
- Which of these failure modes and hazards hold for the sense of purine 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.
- Low-purine diet lists and cut-offs differ by country and by food-composition table, not by a single global food-law definition of "purine content".
- Clinical serum-urate targets and gout-treatment algorithms differ between ACR (US) and EULAR (Europe) practice.
- Nitrogen-excretion biology differs across taxa (uric acid in humans and uricotelic animals versus allantoin in most other mammals), which changes what "purine end-product" means in veterinary versus human settings.
- Which of these regional variation hold for the sense of purine 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.
- pyrimidine - Pyrimidine is a single six-membered diazine; purine is that ring fused to imidazole. Elemental formula and fused-ring numbering separate them.
- pteridine - Pteridine is pyrimidine fused to pyrazine (two six-membered rings); purine is pyrimidine fused to imidazole. Ring-size count and ChEBI/IUPAC parent distinguish them.
- uric acid - Uric acid is a trioxygenated purine catabolite (7,9-dihydro-1H-purine-2,6,8-trione), not the unsubstituted parent; CAS 69-93-2 versus 120-73-0.
- pyridine - Pyridine is a six-membered monoazine with no fused imidazole and only one nitrogen; mass spectrum and nitrogen count separate it from purine.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of purine this model covers, and on what evidence? provenance
Sources
- purines (IUPAC Gold Book) - Specialist definition of the fused heterocyclic parent and its derivatives.
- Purine (compound) - CAS, molecular formula, identifiers, and physicochemical data for the parent compound.
- purine (CHEBI:17258) - Ontology class, tautomer preference, and relationship to nucleobases and nucleotides.
- purine (Q47477) - Cross-registry identifiers (CAS, ChEBI, PubChem, InChIKey).
What the second pass must settle
- Does the registry intend purine to denote the parent compound exclusively, or must this entry also resolve references to the chemical family?
- Which accessible reference materials and analytical methods provide sufficient discrimination of parent purine from likely derivatives and other interfering compounds?
- Which protonation and tautomer assignments are experimentally supported under the conditions relevant to intended uses?
- What reliable evidence establishes solubility, solid forms and stability across the intended storage and preparation conditions?
- Which authoritative handling information and use-specific acceptance criteria apply to the actual purine materials agents will encounter?