Amino acid sequence of a feather keratin from silver gull (Larus novae-hollandiae) and comparison with one from emu (Dromaius novae-hollandiae).

The amino acid sequence of the major components of the silver gull feather calamus has been determined and compared with that of the emu. The sequenator was used with a modified Edman-Begg program to facilitate determination of the sequence of the large hydrophobic fragment obtained on tryptic digestion. The main features of the comparison were: (1) the overall structures of the polypeptide chains were similar, having non-crystalline cystine-rich sections towards either end of the chain separated by a large crystalline region of 62 residues which contained the majority of the hydrophobic and serine and glycine residues; (2) approximately one-sixth of the residues were different in the two species, with the majority of changes occurring in the tails (i.e. non-crystalline or matrix region). The data argue for stringent demands in the selection of amino acids for the crystalline part of the feather molecule, a severity that is probably comparable to the strict requirements for the sequence of some of the enzymes.