collagen

Supported collagen assignment

Captures the strongest supported identity assignment and its unresolved alternatives.

1. Which collagen types and constituent chains are supported by the available identity measurements? definition
2. Can the methods used distinguish the assigned collagen from other proteins and collagen types plausibly present? measurement

Material classification boundary

Records whether the assessed entity is intact collagen, altered collagen or a material containing collagen.

1. What chain-integrity and conformation evidence supports distinguishing this material from gelatin or collagen hydrolysate? boundary
2. Which non-collagen constituents are present, and do reported properties describe collagen itself or the complete mixture? boundary

Traceable collagen source

Records the origin at sufficient resolution to connect a sample with supporting evidence.

1. From which organism and tissue, or recombinant production system, was this collagen obtained? provenance
2. Which source and lot records connect the tested sample to the material proposed for use? provenance

Processing-dependent identity

Connects extraction, purification and modification steps with measured changes.

1. Which extraction, enzymatic treatment, purification, drying and chemical modification steps were applied? provenance
2. What evidence establishes whether those steps changed terminal regions, chain integrity or residual non-collagen content? measurement

Retained molecular structure

Records evidence for structural retention, partial alteration or loss.

1. What measurements support the reported triple-helical state under the current temperature, medium and hydration conditions? measurement
2. What chain-size or cleavage evidence distinguishes denaturation from fragmentation in this sample? measurement

Observed collagen organisation

Captures assembly morphology, orientation and crosslinking without presuming every collagen forms the same structure.

1. Is the collagen dispersed, fibrillar, networked or aggregated, and which observations establish that assignment? measurement
2. Which native or introduced crosslinks are demonstrated, and what is known about their extent and distribution? measurement

Conditioned material state

Makes concentration, swelling and observed structure comparable across measurements.

1. What are the collagen concentration, water content, temperature, pH and medium composition at assessment? measurement
2. Does changing hydration or medium produce reversible swelling or dispersion, or evidence of persistent structural change? measurement

Stability evidence

Connects storage and processing exposures with retained or altered properties.

1. What thermal, chemical, enzymatic, drying or freeze-thaw exposures has this material experienced? provenance
2. Which comparisons with a suitable baseline establish retained integrity or detect denaturation, cleavage or unwanted aggregation? measurement

Demonstrated capability

Bounds capability claims by sample form, test conditions and required performance.

1. Which measured mechanical, swelling, assembly or degradation behaviour is required for the proposed role? action
2. Were those properties demonstrated for this collagen form and lot under conditions representative of that role? measurement

Bounded processing choice

Records supported processing conditions and the checks needed to confirm the result.

1. What evidence supports the proposed dissolution, assembly, crosslinking, shaping or sterilisation conditions while retaining the required collagen properties? action
2. Which post-process measurements determine whether the result remains within this collagen model or should link to a derivative or composite model? boundary

Kinds and varieties

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Type I collagen (bone, tendon, skin, dentin)
• Type II collagen (cartilage, vitreous humour)
• Type III collagen (reticular fibres, blood vessels, skin, uterus)
• Type IV collagen (basement membranes)
• Type V collagen (pericellular fibrils, often with type I)
• Type VI collagen (beaded-filament microfibrils)
• Type VII collagen (anchoring fibrils at the dermal-epidermal junction)
• Hydrolysed / denatured collagen (gelatin and collagen peptides used as ingredients)

1. Which of these kinds and varieties hold for the sense of collagen 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.

• Wikidata - Q26868 - item 'collagen'
• MeSH - D003094 - Medical Subject Headings descriptor Collagen
• ChEBI - CHEBI:3815 - chemical entity 'collagen'
• CAS Registry Number - 9007-34-5 - collagen (generic / extracted protein)
• EC number (EINECS) - 232-697-4 - collagen as a chemical substance in the EU inventory
• INCI - Collagen - cosmetic ingredient name; related names include Hydrolyzed Collagen, Soluble Collagen
• UniProt / gene (human type I) - COL1A1 (P02452), COL1A2 (P08123) - principal genes encoding type I collagen α-chains

1. Which of these identifiers and schemes hold for the sense of collagen 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.

• ISO 3496:1994 - Meat and meat products - Determination of hydroxyproline content (ISO; collagen inferred from hydroxyproline)
• ISO 3496 is the classic meat-chemistry method; later meat-protein / connective-tissue methods sit in ISO TC 34 meat-analysis series
• Ph. Eur. monograph Gelatin (European Pharmacopoeia / EDQM) - identity, bloom, microbial limits for pharmaceutical gelatin
• USP-NF Gelatin (United States Pharmacopeia) - pharmaceutical gelatin quality
• Regulation (EC) No 853/2004, Annex III, Section XIV - hygiene rules for collagen intended for human consumption (EU)
• Regulation (EC) No 2073/2005 - microbiological criteria applicable to collagen and gelatin for food use (EU)
• Regulation (EC) No 1223/2009 - cosmetic products; collagen ingredients listed by INCI with safety assessment (EU)
• 21 CFR 182.1 / GRAS framework and 21 CFR 172 (food additives) as applied to gelatin and collagen hydrolysates in the United States (FDA)
• ISO 22442 series - Medical devices utilizing animal tissues and their derivatives (ISO; TSE/viral risk for animal-derived collagen implants)
• ASTM F2212 - Standard Guide for Characterization of Type I Collagen as Starting Material for Surgical Implants and Substrates (ASTM International)

1. Which of these standards and regulation hold for the sense of collagen 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.

• Structural protein of skin, bone, tendon, ligament, cartilage, cornea, blood-vessel wall and basement membranes in vertebrates
• Extracted bovine, porcine, piscine or recombinant collagen used as haemostatic sponges, wound dressings, dermal fillers, bone-graft matrices and tissue-engineering scaffolds
• Converted by heat/acid/alkali to gelatin for food (gelling, clarification), capsules and photographic/technical films
• Enzymatically hydrolysed collagen peptides sold as nutraceuticals and sports-nutrition ingredients
• Cosmetic moisturizers and film-formers labelled Collagen, Soluble Collagen or Hydrolyzed Collagen
• Leather and parchment are collagen-fibre networks of animal hide after tanning or drying
• Analytical marker of connective-tissue content in meat (hydroxyproline) and of animal glue in heritage conservation

1. Which of these real-world use hold for the sense of collagen 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.

• Hydroxyproline content (as a collagen proxy) - about 12-14% of collagen amino-acid residues; conversion factors ~7.1-8.0 g collagen per g hydroxyproline depending on tissue - g/100 g protein or conversion factor (dimensionless)
• Triple-helix denaturation / melting temperature (Tm or Td) - mammalian type I ~37-42 °C in dilute solution; fibrillar collagen in tissue higher; fish collagens often ~15-30 °C - °C
• Fibril D-period (axial banding) - 67 (typically 64-67) - nm
• Molecular mass of a tropocollagen molecule - about 300 (three ~95-140 kDa α-chains) - kDa
• Molecule length × diameter (tropocollagen) - about 300 × 1.5 - nm
• Gelatin Bloom strength (derived product) - food/pharma gelatin commonly 50-300 - Bloom (g)
• Isoelectric point of native collagen - roughly 7-9 depending on type and telopeptide status; atelocollagen and gelatin lower and more variable - pH

1. Which of these typical measurements hold for the sense of collagen 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.

• Thermal or chemical denaturation unravels the triple helix, converting collagen to gelatin and collapsing tensile strength
• Enzymatic degradation by matrix metalloproteinases (MMP-1, MMP-8, MMP-13 collagenases) and bacterial collagenases in wound infection
• Cross-link deficiency (scurvy / lysyl-oxidase impairment) yields fragile vessels, poor wound healing and bone fragility
• Excess or disordered deposition (fibrosis, keloid, scleroderma, cirrhosis) stiffens organs
• Pathogenic variants in COL genes cause osteogenesis imperfecta, Ehlers-Danlos syndromes, Alport syndrome, dystrophic epidermolysis bullosa and Stickler syndrome
• Bovine- or ovine-sourced collagen and gelatin carry residual TSE (BSE/scrapie) risk unless sourced and processed under specified animal-tissue rules
• Immunogenicity and delayed hypersensitivity to heterologous (especially bovine) injectable collagen
• Heavy-metal, microbial or residual-chemical contamination of poorly processed food/cosmetic hydrolysates
• Over-hydrolysis of peptides destroys gelling function; under-hydrolysis leaves insoluble, poorly digestible fractions

1. Which of these failure modes and hazards hold for the sense of collagen 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.

• Food and cosmetic collagen is commonly bovine or porcine in Europe and the Americas; fish-skin/scale collagen is preferred where porcine/bovine sources are religiously restricted (halal/kosher markets) or where BSE controls limit cattle tissue
• Japan, South Korea and parts of Southeast Asia have a large market for marine collagen peptides in beauty and functional foods
• EU food-hygiene law treats 'collagen' as a named product of animal origin with plant-approval and raw-material rules; US practice more often regulates the derived gelatin or hydrolysate under food-additive/GRAS and device frameworks
• Traditional animal glue (hide/bone glue) remains a named craft material in Europe and East Asia, while industrial users may simply specify 'gelatin' or 'collagen hydrolysate'
• Clinical injectable fillers: bovine collagen (historical Zyderm/Zyplast) largely displaced in many markets by hyaluronic acid; recombinant and porcine atelocollagen remain in some Asian and surgical-scaffold uses

1. Which of these regional variation hold for the sense of collagen 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.

• Gelatin - Gelatin is heat-denatured, water-soluble collagen that has lost the native triple helix and fibrillar D-banding; it gels on cooling. Native collagen remains insoluble fibrils with a collagenase-sensitive helix and ~67 nm banding on TEM.
• Elastin - Elastin is a hydrophobic, rubber-like ECM protein rich in desmosine/isodesmosine cross-links and low in hydroxyproline; collagen is glycine-rich, hydroxyproline-rich and tensile rather than elastic. Distinguish by amino-acid composition and by elastase vs. bacterial collagenase susceptibility.
• Keratin - Keratin is an intermediate-filament protein of epithelia and epidermal appendages (hair, nail, horn), rich in cysteine disulfides, not a Gly-X-Y triple helix. Collagen is mesenchymal/ECM and hydroxyproline-positive.
• Fibronectin - Fibronectin is a modular adhesive glycoprotein that binds integrin and collagen but is not itself a triple-helical fibril; it is identified by FN1 immunoreactivity and SDS-PAGE ~220-250 kDa subunits, not by hydroxyproline.
• Chitosan / plant 'collagen' marketing substitutes - True collagen is animal (or recombinant animal-sequence) protein with hydroxyproline and a triple helix. Plant hydrocolloids, yeast extracts and chitosan lack the collagen Gly-X-Y helix; hydroxyproline assay and circular-dichroism triple-helix signature separate them.
• Reticulin (historical stain term) - Silver-staining 'reticulin fibres' are largely type III collagen microfibrils, not a separate protein; immunohistochemistry for type III vs type I collagen replaces the old stain-only distinction.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of collagen this model covers, and on what evidence? provenance