title: Limited proteolysis of the 94 000-dalton subunit of Panulirus interruptus hemocyanin; the carbohydrate attachment site.
abstract: Limited proteolysis of the native monomeric 94-kDa subunit of Panulirus interruptus hemocyanin by trypsin, plasmin and subtilisin produces an 18-kDa fragment, a 71-kDa fragment and a small glycopeptide. In the plasmin digest a 23-kDa precursor of the 18-kDa fragment has been observed. Automatic Edman degradations demonstrated that the 18-kDa fragments have their origin at the N terminus of the 94-kDa subunit and incubations with carboxypeptidase A showed that the 71-kDa fragments originate from the C terminus. The glycopeptide is situated in between. The amino acid sequence of the glycopeptide has been determined. Its carbohydrate content accounts for the total carbohydrate of the 94-kDa subunit. All three proteases cleave the subunit at two positions within a very restricted area of the polypeptide chain, which indicates the presence of an exposed loop, carrying the carbohydrate chain, in the corresponding part the native molecule.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002241:Carbohydrates / Q000032:analysis*; D005341:Fibrinolysin; D006020:Glycopeptides / Q000032:analysis; D006433:Hemocyanins / Q000032:analysis*; D006458:Hemolymph / Q000032:analysis; D008121:Nephropidae / Q000032:analysis*; D010446:Peptide Fragments / Q000032:analysis*; D013381:Subtilisins; D014357:Trypsin
chemical_list: D002241:Carbohydrates; D006020:Glycopeptides; D010446:Peptide Fragments; D006433:Hemocyanins; D013381:Subtilisins; D014357:Trypsin; D005341:Fibrinolysin