tailieunhanh - Báo cáo khoa học: Purification, characterization and molecular cloning of tyrosinase from the cephalopod mollusk, Illex argentinus

Tyrosinase (monophenol,L-DOPA:oxygen oxidoreductase) was isolated from the ink of the squid,Illex argentinus. Squid tyrosinase, termed ST94, was found to occur as a covalently linked homodimeric protein with a molecular mass of kDa containing two copper atoms per a subunit. The tyrosinase activity of ST94 was enhanced by proteolysis with trypsin to form a protein, termed ST94t, with a molecular mass of kDa. | Eur. J. Biochem. 270 4026-4038 2003 FEBS 2003 doi Purification characterization and molecular cloning of tyrosinase from the cephalopod mollusk Illexargentinus Tetsushi Naraoka1 2 Hidemitsu Uchisawa1 Haruhide Mori2 Hajime Matsue3 Seiya Chiba2 and Atsuo Kimura2 1 Aomori Industrial Research Center Aomori 2Division of Applied Bioscience Graduate School of Agriculture Hokkaido University Sapporo 3Aomori University of Health aid Welfare Aomori Japan Tyrosinase monophenol L-DOPA oxygen oxidoreductase was isolated from the ink of the squid Illex argmtinus. Squid tyrosinase termed ST94 was found to occur as a covalently linked homodimeric protein with a molecular mass of kDa containing two copper atoms per a subunit. The tyrosinase activity of ST94 was enhanced by proteolysis with trypsin to form a protein termed ST94t with a molecular mass of kDa. The amino acid sequence of the subunit was deduced from N-terminal amino acid sequencing and cDNA cloning indicating that the subunit of ST94 is synthesized as a premature protein with 625 amino acid residues and an 18-residue signal sequence region is eliminated to form the mature subunit comprised of 607 amino acid residues with a deduced molecular mass of 68 993 Da. ST94 was revealed to contain two putative copper-binding sites per a subunit that showed sequence similarities with those of hemocyanins from mollusks tyrosinases from microorganisms and vertebrates and the hypothetical tyrosinase-related protein of CaenorhJbditis elegans. The squid tyrosinase was shown to catalyze the oxidation of monophenols as well as o-diphenols and to exhibit temperature-dependency of o-diphenolase activity like a psychrophilic enzyme. Keywords Illex argentinus tyrosinase copper protein melanogenesis cephalopod. Tyrosinase monophenol L-DOPA oxygen oxidoreductase is one of the copper-containing phenoloxidases that are widely distributed in nature. The enzyme is known to be a key enzyme in the .