Abstract:

Myeloperoxidase (MPO) is widely distributed in phagocytes of vertebrates, which mainly functions in catalysing chloride and hydrogen peroxide to produce hypochlorous acid, a potent antimicrobial agent in polymorphonuclear neutrophils. Currently, little is known about MPO of fish and other lower vertebrates. In the present paper, the fulllength cDNA of MPO was cloned from mandarin fish by utilizing reverse transcriptasepolymerase chain reaction and rapid amplification of cDNA ends. The results showed that the fulllength of mandarin MPO cDNA was 3?345 nucleotides (nt), with an open reading frame of 2292 nt encoding 763 amino acids. Although amino acid sequence comparison of MPO of mandarin with those of mammals demonstrated that their similarity (64%～65%) was not very high, their molecular weights were quite approximate. Like mammals, the MPO of mandarin fish also posessed one hemachrome group, one conserved banding calcium site, six intramolecule disulfide bridges and six Nglycosylation sites, implying that it may function as same as its mammalian counterpart. On the other hand, partial cDNA sequence of mandarin MPO was expressed in Escherichia coli rosettagami (DE3) using a recombinant expression plasmid pETMPO, and the combinant protein was purified by the Ni2NTA resin using it's Nterminal HisTag.

Key words: myeloperoxidase； gene clone； Siniperca chuatsi； prokaryotic expression