Atlantic Cod Trypsin Y-Member of a Novel Trypsin Group.

A unique trypsinogen complementary DNA has been isolated from an Atlantic cod (Gadus morhua) cDNA library. Its predicted amino acid sequence contains 249 residues with a putative polypeptide of 227 residues. The distinctive features of this polypeptide, referred to as trypsin Y, are its low number of hydrogen-bond-forming residues, high content of Met and Pro residues, and lack of one conserved disulfide bond. Alignments show that cod trypsinogen Y has only approximately 45% identity to the two Atlantic cod trypsinogens I and X and most vertebrate trypsinogens. However, it has more than 70% identity to three other fish trypsinogens from two Pleuronectes and an Antarctic Notothenia species. These four trypsinogens share some unique characteristics and form a novel group, here referred to as group III.