A search for a simple keratin—fractionation and peptide mapping of proteins from feather keratins

Abstract

S-Carboxymethylated (SCM) proteins have been prepared from the various morphological parts of the feathers (a natural β-keratin) from one species of bird and also from the calami of feathers from several species of birds. The complexity of the extracts has been examined by acrylamide-gel electrophoresis and size-charge peptide maps of radioactively labelled SCM-peptides in enzyme digests of the extracts. The results suggest that (1) the protein mixture from the natural β-keratins such as feather is simpler than that from β-keratins such as wool and prekeratin proteins of epidermis; (2) the proteins extracted from the emu calamus (or rachis) and silver gull calamus are simpler in their acrylamide-gel pattern than those from fowl or goose feather calamus, (3) the peptide maps of radioactively labelled SCM-peptides of the feather extracts studied (emu, silver gull, and goose calamus) are no more complex than those from the homogeneous protein SCM-lysozyme which has approximately the same number of Scarboxymethylcysteine residues per molecule, and this indicates that the protein components corresponding to the bands in the acrylamide-gel electrophoresis patterns of the feather extracts could be homogeneous; (4) the rachis and calamus proteins, which are probably identical, form one class of proteins while the barbs and medullary proteins form another class but are not identical. The proteins corresponding to the bands seen in acrylamide-gel patterns of SCM-proteins extracted from emu feather calamus and rachis have been separated by chromatography on columns of DEAE-cellulose. It is necessary to use buffers containing 8M urea. The proteins have very similar amino acid compositions but a difference can be seen in peptide maps of protein band 2 and protein band 3. © 1973 CSIRO.