Pepsin Digestion for Proteomic Studies of the Human Hair Shaft

Spectral counting on trypsin-based proteomics has been widely used to study the stoichiometry of protein complexes. For the first time, we confirmed a large bias caused by the trypsin enzyme in spectral counting. We further demonstrated that the use of pepsin can effectively correct such bias. In addition, we discovered that pepsin digestion can better identify keratin-associated proteins than trypsin proteolysis, which offers another effective tool for studying the hair proteome.