The evolution of keratin proteomics

Coined in the 1990s proteomics is the study of the expressed protein component of the genome of any organism at a certain point in time. In the case of its application to keratin proteins in hair and wool fibers, proteomics has undergone considerable evolution starting with one-dimensional gel electrophoretic separation, through to non-equilibrium and then electrofocusing-based two-dimensional electrophoresis, to gel-free proteomic approaches.

At the same time the identification of proteins by these techniques has also moved from the application of amino acid analysis to mass spectrometric approaches, the latter starting with peptide mass fingerprinting through to the present-day approach of sequencing of peptides after a second fragmentation of the peptide inside the mass spectrometer. All of this has been aided by the generation of a near complete set of sequence information for keratins and the keratin associated proteins, something that was not available 30 years ago. Keratin proteomics has also become more than the simple cataloguing exercise that existed then towards a wider range of applications that look at protein structure, protein abundance and protein modification. For instance it has been used to develop an understanding of how stretching and other processes affect the readily accessible disulfide bonding in the fiber and hence which ones are potentially involved in inter- and intra-molecular crosslinking. Another approach has seen the application of the label-free quantitative approach to determine differences of relative abundances of proteins between wild-type and crimp mutant animals as part of an overall investigation into the basis of fiber curvature.