Hemocyanin is a large, copper-containing protein present in the hemolymph of both mollusks and arthropods. The traditional role of hemocyanin is the transport and storage of molecular oxygen. Today, it is known that hemocyanin is a multifunctional protein, especial function related to antivirus, antimicrobial and antifungal immune responses. A partial coding sequence of cDNA encoding hemocyanin consisted of 1470 nucleotides including stop codon and 3'-UTR is available from GenBank with accession number AF431737. In this study, the authors cloned and sequenced of the full length cDNA encoding syntenin from WSSS infected black tiger shrimp. Using 5'RACE technique, the authors determined 5'-end sequence including initial codon and 5'-UTR. Based on the 5'-end sequence and the GenBank sequence (AF431737), the complete hemocyanin cDNA was cloned and sequenced. The coding region of hemocyanin cDNA was 2052 bp in length, and was predicted to encode a 683 amino acid protein. The putative protein contains 3 domains and 6 conversed histidines to set structure and function. The result of nucleotide sequence alignment between the newly determined hemocyanin sequence and that of WSSV infected Penaeus monodon isolated in India showed that there are 33 different nucleotides in the two sequences. The nucleotide differences were found to result in 7 amino acid substitutions including 242H-D, 304N-D, 360V-I, 443K-L, 453Y-F, 472A-P and 576G-A. The results would be useful for further study of the function of hemocyanin and related proteins in the shrimp immune response.
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