Determination and validation of markers for heat-induced damage in wool proteins

Abstract

Protein-based animal fibres of commercial importance are frequently exposed to elevated temperatures during processing treatments. Hydrothermal processes cause protein deterioration, impacting negatively on the value or condition of these materials. This study was designed to investigate hydrothermal damage in wool proteins at the molecular level. The effect of hydrothermal damage on Type I and II intermediate filament proteins (keratins) extracted from wool was characterised using advanced quantitative techniques based on isobaric iTRAQ labelling and mass spectrometry. Many native peptides were observed to be degraded and modified. Amongst these, twenty keratin peptides were observed to consistently degrade during hydrothermal exposure. These peptides acted as molecular markers of damage—specific indicators of the extent of heat-induced protein damage. This technology will be of value in assessing the severity of damage imparted after high temperature exposure of protein-based animal fibres such as wool and cashmere during processes such as dyeing and carbonising, or even after high temperature human hair treatments. The identification of molecular damage markers identified within wool and other materials provides a new route to sensitive and specific evaluation of the effects of protein deterioration. It is anticipated that the utilisation of such markers will facilitate the development of targeted approaches to minimising processing damage to high-value fibres and protein-based biomaterials.