Proteomic Identification Principles for Animal Hair Fibre Mixes
Proteomic LC-MS/MS quantifies animal hair blend percentages by measuring species-specific keratin peptide markers against isotope-labeled internal standards.
KRT31
Keratin Composition
High-molecular-weight structural proteins forming the protective cuticular layer of mammalian hair fibres function as biochemical markers for animal species identification in luxury textiles. In the commercial testing of knitwear, krt31 is analyzed to determine the presence of authentic wool and sheep hair. This acidic type I keratin constitutes a major portion of the intermediate filaments within the fibre shaft.
Proteomic Signature
Amino acid sequences within this specific protein remain highly conserved yet vary enough between animal species to allow precise taxonomic differentiation. Analysts use trypsin digestion to break down krt31 into unique peptide fragments that can be separated and detected using liquid chromatography mass spectrometry. This molecular method overcomes the limitations of scanning electron microscopy, which often fails when fibres are damaged by bleaching, heavy dyeing, or aggressive mechanical finishing.
Consequently, the signature remains reliable across various fabric grades.
Fibre Profiling
Forensic laboratory tests identify cashmere, mohair, and sheep wool by mapping these specific keratin proteins. Because krt31 is abundant and highly stable, it resists the harsh chemical processing of dyeing and scouring, enabling the reliable testing of finished garments. This resilience ensures that even old or heavily processed fabrics can be analyzed for fibre content and authenticity.
Supply Verification
Brand quality assurance divisions mandate these proteomic assays to verify raw material declarations from fabric mills. The presence of specific krt31 peptides indicates whether a sample consists of genuine wool or is contaminated with lower-grade sheep fibres. Such continuous testing maintains the integrity of high-end woollen supply chains.