Amino Acid Sequence Studies on Bobwhite Quail Egg White Lysozyme

Autor: Ellen M. Prager, Allan C. Wilson, Norman Arnheim, George A. Mross
Rok vydání: 1972
Předmět:
Zdroj: Journal of Biological Chemistry. 247:2905-2916
ISSN: 0021-9258
DOI: 10.1016/s0021-9258(19)45297-6
Popis: To test the immunological prediction that there should be two amino acid sequence differences between the lysozymes of the bobwhite quail and the chicken, the sequences of these two lysozymes have now been compared. Lysozyme purified from bobwhite quail egg white was reduced, carboxymethylated, and digested with trypsin. The resulting 18 peptides were separated and their compositions determined. Four of them differed in composition from the corresponding chicken egg white lysozyme peptides. The compositional differences could be accounted for by four amino acid substitutions. The positions at which the substitutions relative to chicken lysozyme occur were found by analysis and sequential degradation of these four tryptic peptides to be serine for threonine40, valine for isoleucine55, lysine for arginine68, and threonine for serine91. It is remarkable that three of the four interchanges appear from the three-dimensional model of chicken lysozyme to have occurred at buried positions. The remaining interchange, lysine for arginine68, has occurred at an exposed position and in a region shown by others to bear an antigenic determinant. The implications of the bobwhite quail sequence information with respect to the sequence-immunology correlation, lysozyme evolution, and the phylogeny of phasianoid birds are discussed.
Databáze: OpenAIRE