Amino acid sequences of ovomucoid third domain from 25 additional species of birds

Ovomucoids were isolated from 25 avian species other than the 101 studied in Laskowski et al. (1987, Biochemistry 26, 202-221). These were subjected to limited proteolysis with an appropriate enzyme, and connecting peptide extended ovomucoid third domains were isolated and sequenced to the end in a protein sequencer. Of the 25 new sequences, 13 duplicate ones were already known, and 12 are unique. Probably the most striking findings are a Pro14----Ser14 replacement in weka, an Ala14----Thr15 replacement in Bulwer's pheasant, the discovery of two additional amino acid residues Ile18 and Gly18 at the P1 reactive site position in Kalij pheasant and tawny frogmouth, respectively, and the first finding of a negative (Glu34) rather than positive (Lys34 or Arg34) amino acid residue at the NH2 terminus of the alpha helix in caracara ovomucoid third domain. These results complete the determination of all the sequences of ovomucoid third domains in the four species genus Gallus, in the five species genus Syrmaticus, and in the two species genera Aix and Pavo.