Panulirus interruptus hemocyanin. The elucidation of the complete amino acid sequence of subunit a

Abstract

As a final step in the elucidation of the primary structure of subunit a of Panulirus interruptus hemocyanin (657 residues, M_r 75696 excluding two copper ions and carbohydrate), the amino acid sequence of the largest fragment obtained by limited trypsinolysis was determined. The elucidation of the sequence of residues 176–657, comprising domains two and three, was mainly based on two digests, with CNBr and trypsin, respectively, from both of which a complete set of peptides was obtained. Additional sequence information was obtained from a digest with Staphylococcus aureus V8 protease and from one fragment obtained by cleaving subunit a with hydroxylamine. A block during Edman degradations indicated an Asn‐Gly sequence at positions 597–598, although only aspartic acid was identified at position 597.