guanine
Enable an agent to recognise guanine, assess the identity and condition of a guanine material, and judge its suitability for a specified chemical, biological or optical 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.
recalled by Codex without web access - no source was read
Researched by: Codex
Purpose and description
Enable an agent to recognise guanine, assess the identity and condition of a guanine material, and judge its suitability for a specified chemical, biological or optical use.
Guanine is a purine nucleobase with molecular formula C5H5N5O that occurs as a component of DNA and RNA and forms canonical Watson-Crick base pairs with cytosine.
It can be Identify a sample as guanine using structure-linked records and suitable analytical evidence.; Accept, reject or qualify a guanine lot against the purity and impurity requirements of an intended use.; Assess and select dissolution conditions while recording the resulting chemical form and concentration.; Evaluate guanine particles for a specified dispersion or optical application using measured morphology and solid-state evidence.; Detect chemical alteration or contamination and determine whether further characterisation is required.; Select handling and storage measures from verified information applicable to the actual material..
Distinguishing features
Establish the 2-amino-6-oxopurine connectivity; elemental composition alone does not distinguish structural isomers.
Confirm the molecular formula C5H5N5O for neutral guanine and distinguish it from adenine, hypoxanthine and xanthine.
Check for an attached sugar or sugar-phosphate group: these identify a nucleoside or nucleotide rather than free guanine.
Distinguish an isolated guanine material from guanine residues detected within a nucleic acid.
Identify whether a crystalline or reflective sample is guanine itself, a mixture containing guanine or a finished pigment formulation.
Scope
+ Guanine molecular identity, distinguishing the free nucleobase from derivatives and incorporated residues
+ Purity, impurities, water content and grade of guanine samples
+ Solid forms, particle properties and condition-dependent dissolution
+ Chemical transformations and molecular interactions relevant to handling or use
+ Source, analytical evidence and applicable safety or regulatory records
- Guanosine, deoxyguanosine and guanine nucleotides as independently identified substances
- DNA and RNA sequences, structures and biological functions
- Purine biosynthesis, salvage and degradation pathways as complete processes
- Organisms and tissues that produce or contain guanine
- Finished cosmetics, pigments, assay kits and other guanine-containing products
Characteristics
- Chemical identity and identifier agreement
- Structure representation, molecular formula, verified CAS number, PubChem CID and EC identifier where applicable Prevents records for guanine, related purines and derivatives from being merged.
- Chemical presentation
- Free base, protonated or deprotonated species, salt, hydrate or other explicitly identified form Determines whether the material belongs directly to this model or requires a related substance record.
- Assay and impurity profile
- Mass fraction or method-specific assay percentage; individual impurities in mg/kg or another stated unit Supports decisions about analytical, biological and material applications without equating chromatographic area with mass purity.
- Water and residual solvent content
- Mass percent or mg/kg, with analytical method Affects weighed concentration, storage behaviour and interpretation of solid-form measurements.
- Solid-state identity
- Experimentally assigned crystalline form, amorphous material or unresolved form Connects dissolution and optical behaviour to the material actually examined.
- Particle morphology and size
- Dimensions and size distribution in µm; shape and aspect ratio Supports assessment of dispersion, dissolution and reflective performance.
- Solubility under specified conditions
- mol/L or g/L, with solvent, pH, temperature, solid form and equilibration method Determines whether a requested preparation can produce a solution at the required concentration.
- Thermal behaviour
- Transition or decomposition temperature in °C, with method, atmosphere and heating rate Prevents decomposition events from being reported as usable melting or boiling points.
- Sample condition
- Within specification, contaminated, chemically altered or unassessed, with dated evidence Separates the identity of guanine from the present usability of a particular sample.
- Safety and regulatory identity
- Links to applicable SDS, jurisdiction-specific classification, exposure-limit records and product or grade restrictions Makes handling decisions traceable while distinguishing an absent classification from missing information.
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 · 16 findings · 26 questions.
Guanine identity and boundaries Establishes which molecular entity and material presentation the record describes.
Guanine is easily conflated with its nucleosides, nucleotides and residues in biological polymers.
Purine molecular identity
Captures the structure evidence that distinguishes guanine from related purines.
Structure-linked identification
Record guanine connectivity and reconcile names and identifiers against that structure.
- Which verified structure representation identifies this record as 2-amino-6-oxopurine? definition
- Which authoritative records establish the CAS, PubChem and EC identifiers for the precise chemical form? provenance
Free base and related entities
Separates guanine itself from chemically linked or formulated presentations.
Entity boundary test
Determine whether the subject is free guanine, a related substance or a containing material.
- Is the guanine present as a free nucleobase, a sugar-linked derivative or a residue within DNA or RNA? boundary
- Does a counterion, covalent modification or formulation require a separate linked substance or product model? boundary
Guanine lot composition Describes the origin and measured composition of a particular guanine material.
A guanine label does not establish assay value, freedom from related purines or suitability for a sensitive application.
Origin and grade
Connects the material to its production route, supplier and declared specification.
Lot origin and specification
Record traceable origin and grade claims without treating the grade name as analytical proof.
- Was this lot synthesised, isolated from a biological source or obtained by another documented route? provenance
- Which lot-specific certificate and specification define the claimed grade and intended use? provenance
Assay and related purines
Distinguishes guanine content from water, residual solvents and chemically related contaminants.
Composition evidence
Record quantitative composition with methods capable of resolving relevant impurities.
- What is the guanine assay, on what reporting basis, and can the method distinguish guanine from adenine, hypoxanthine and xanthine? measurement
- What water, residual solvent and other impurity measurements are needed to accept this lot for its intended application? action
Guanine physical form and preparation Relates the actual solid material to dissolution and thermal behaviour.
Preparation decisions require condition-specific measurements rather than a single unqualified solubility or transition value.
Solid form and thermal events
Characterises solid-state identity and distinguishes transitions from chemical decomposition.
Solid-state evidence
Attach measured solid-form assignments and correctly interpreted thermal observations.
- Which diffraction, spectroscopic or thermal evidence identifies the sample's crystalline form and hydration state? measurement
- Does the reported heating event represent melting, solvent loss, a solid-state transition or decomposition under the stated conditions? measurement
Dissolution and speciation
Connects achievable concentration to solvent conditions and chemical form.
Qualified solution preparation
Assess dissolution using explicit pH, temperature, concentration and stability requirements.
- What equilibrium solubility is supported for the specified solvent, pH, temperature and starting solid form? measurement
- Will the preparation remain dissolved at the final working pH and temperature, and what guanine species will be present? action
Guanine interactions and performance Captures use-relevant molecular interactions and particle-dependent optical behaviour.
Guanine's biological recognition and reflective material uses depend on different physical contexts that must be recorded explicitly.
Molecular recognition context
Qualifies claims about pairing, association and chemical transformation by molecular context.
Interaction and transformation evidence
Separate evidence about free guanine from evidence about guanine incorporated into larger molecules.
- Does the cited interaction with cytosine or another partner concern free guanine, a nucleoside or a nucleic-acid residue? boundary
- What evidence establishes association or transformation under the solvent, pH and chemical conditions of the proposed use? measurement
Crystal optical performance
Relates guanine particle structure and arrangement to measured optical effects.
Reflective particle qualification
Assess optical suitability using measurements of the particles and their application environment.
- What particle dimensions, crystal form, orientation and surrounding medium accompany the measured reflectance or scattering? measurement
- Which acceptance criteria determine whether these guanine particles are suitable for the proposed optical application? action
Guanine condition and permitted use Connects storage history, chemical integrity and applicable handling requirements to use decisions.
Neither molecular identity nor a supplier grade alone establishes present condition or permission for a particular application.
Integrity during storage and use
Tracks evidence of contamination or chemical alteration in solid guanine and prepared solutions.
Condition and requalification
Record relevant exposure history and analytical criteria for continued use.
- What storage duration, temperature, solution pH and exposure to reactive substances are documented for this material? provenance
- Which analytical changes or missing records require requalification before the next use? action
Safety and jurisdiction
Links the precise material to current safety evidence and application-specific regulatory requirements.
Applicable handling evidence
Ground handling and use decisions in records covering the actual chemical form, grade and jurisdiction.
- Which current SDS and jurisdiction-specific records establish hazard classification and any applicable exposure limits for this material? provenance
- What handling, storage, disposal and application restrictions follow for the proposed quantity, physical form and intended 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.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- This record is based on recall; no sources were consulted.
- Verify grade, purity, hydration state and measurement conditions before adding physical-property values.
- Confirm supplier-specific safety classifications and jurisdiction-specific requirements; nucleic-acid damage mechanisms are not a hazard classification for bulk guanine.
- Which of these check these first hold for the sense of guanine this model covers, and on what evidence? provenance
Identifiers and schemes
Recalled without web access and unsourced; every item is a lead to verify.
- CAS Registry Number - 73-40-5 - Identifies guanine as the free nucleobase.
- Nucleic-acid base notation - G - Denotes guanine in nucleotide sequences; a sequence position represents a nucleotide residue rather than an isolated free base.
- Which of these identifiers and schemes hold for the sense of guanine this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Used as a reagent and analytical reference in nucleobase chemistry and biochemical research.
- Crystalline guanine provides reflective material in some pearlescent pigments.
- Biological guanine crystals act as reflectors in structures such as fish scales.
- Which of these real-world use hold for the sense of guanine this model covers, and on what evidence? provenance
Typical measurements
Recalled without web access and unsourced; every item is a lead to verify.
- Molar mass - 151.13 - g/mol
- Which of these typical measurements hold for the sense of guanine this model covers, and on what evidence? provenance
Failure modes and hazards
Recalled without web access and unsourced; every item is a lead to verify.
- Low aqueous solubility can limit preparation of concentrated solutions; solubility depends on pH and conditions.
- Oxidation of guanine residues in nucleic acids can produce lesions such as 8-oxoguanine that promote incorrect base pairing.
- Deamination converts guanine to xanthine, altering the chemical identity of the base.
- Which of these failure modes and hazards hold for the sense of guanine this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- guanosine - Guanosine is the nucleoside formed by attaching guanine to ribose.
- guanine nucleotides - Guanine nucleotides contain a guanine base, a sugar and one or more phosphate groups.
- adenine - Adenine is another purine nucleobase; it lacks guanine's carbonyl oxygen and canonically pairs with thymine or uracil.
- cytosine - Cytosine is guanine's canonical pairing partner and has a single pyrimidine ring rather than a fused purine ring system.
- xanthine - Xanthine has a carbonyl group in place of guanine's exocyclic amino group.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of guanine this model covers, and on what evidence? provenance
What the second pass must settle
- Which authoritative identifier records distinguish neutral guanine from separately registered salts, hydrates or other forms?
- Which reported solid forms and thermal values have sufficient experimental evidence, and which apparent melting-point records actually describe decomposition?
- What reliable solubility and speciation data cover the pH, temperature and solvent ranges needed for intended uses?
- Which validated assays and impurity limits distinguish acceptable guanine grades for analytical, biological and optical applications?
- What current hazard classifications, exposure limits and application-specific restrictions apply in the relevant jurisdictions?