MODELS OF THE 3-DIMENSIONAL STRUCTURES OF ECHIDNA, HORSE, AND PIGEON LYSOZYMES - CALCIUM-BINDING LYSOZYMES AND THEIR RELATIONSHIP WITH ALPHA-LACTALBUMINS

Similarities in amino acid sequences, three-dimensional structures, an d the exon-intron patterns of their genes have indicated that c-type l ysozymes and alpha-lactalbumins are homologous proteins, i.e., descend ed by divergent evolution from a common ancestor. Like the alpha-lacta lbumins, echidna milk, horse milk, and pigeon eggwhite lysozymes all b ind Ca(II). Models of their three-dimensional structures, based on the ir amino acid sequences and the known crystal structures of domestic h en eggwhite and human lysozymes and baboon and human alpha-lactalbumin s, have been built. The several structures have been compared and thei r relationships discussed.