PHENOLOXIDASES FROM PINK AND WHITE SHRIMP: KINETIC AND OTHER PROPERTIES

Abstract

Phenoloxidases (PO) were isolated and purified from white shrimp (Panaeus setiferus) and pink shrimp (P. duorarum). The enzyme from each source migrated as a single protein band in polyacrylamide gels with molecular weights of 30,000 for white shrimp PO and 40,000 for pink shrimp PO. Both enzymes were inhibited by p-amino benzoic acid and NaN3. Pink shrimp PO oxidized DOPA at rates 1.8 fold faster than white shrimp PO. Free amino acid analyses of shrimp carapace indicated that pink shrimp had relatively higher levels of tyrosine and phenyialanine, the natural substrates of melanosis, than white shrimp.