Cyanogen bromide cleavage of proteins in sodium dodecyl sulphate/polyacrylamide gels Diagonal peptide mapping of proteins from epidermis

Publisher Website
Google Scholar
Abstract
A 2-dimensional electrophoretic procedure employing CNBr was devised for the analysis of proteins in sodium dodecyl sulfate/polyacrylamide gels. The technique allows the detection of an unusual class of epidermal proteins that lack methionine. The proteins were identified by this method in newborn mouse, rat, and rabbit, because they are stable in the presence of CNBr and consequently lie on a diagonal. Adult human epidermis also contains CNBr-stable proteins, but in lesser amounts than in the newborn rabbit or newborn rodents. The methionine-containing proteins (i.e., the keratins) are degraded by CNBr into a series of unique and characteristic peptides which lie below the diagonal. Inter- and intra-species similarities and differences exist between the individual keratins, depending on the number and distribution of their methionine residues. The peptide-map patterns for the rodent and lagomorph proteins are more similar to each other than to that for the human proteins. The maps for rat and rabbit skin proteins are the most similar. The epidermal keratins are a closely related, yet individually distinct, group of proteins that are found in conjunction with a class of proteins that lack methionine. The latter proteins are related to the histidine-rich basic protein, an epidermal structural protein that aggregates with keratin filaments.