Abstract:
A snake venom L-amino acid oxidase(SV-LAO) gene from Gloydius intermedius cDNA library was bioinformatically analyzed. The results showed that the open reading frame of cDNA is 1 515 bp, encoding 504 amino acids. The primary structures of LAOs between Gloydius halys and Gloydius intermedius showed the highest identity (99%). The N-terminal 18 amino acids is the signal peptide, so the mature peptide contains 486 amino acids, with the theoretical molecular weight and isoelectric point being 55.1 kDa and 6.55, respectively. GI-LAO contains two domains, ie. FAD binding domain and catalytic domain. A comparison of the primary structures between GI-LAO with GH-LAO (LAO of Gloydius halys) revealed that there are four amino acids differences(20, 56, 99 and 467). Online analysis with SIFT software indicated that these differences have no influence on the function of GI-LAO. The key residues in the active site are H242 and R343. The potential N-glycosylation sites are N190 and N379. Five residues(R108, H241, Y390, G482,W483) form the substrate binding sites. The four conserved Cys residuces are presumably to form two disulfide bonds (C28—C191 and C349—C430). Tertiary structure remodelling revealed that GI-LAO is composed of 22 ɑ-helixes, 22 β-strands, turns and loops, which may then refold into three domains(the FAD-binding domain, the substrate-binding domain and the α-helical domain). The GI-LAO protein phylogenetic tree indicates a closest relationship between Gloydius halys and Gloydius intermedius. These bioinformatical analysis would lay the foundation for further investigation of GI- LAO as anti-viral agent.
