title: Crystal structures and amidolytic activities of two glycosylated snake venom serine proteinases.
abstract: We deduced that Agkistrodon actus venom serine proteinases I and II, previously isolated from the venom of A. acutus (Zhu, Z., Gong, P., Teng, M., and Niu, L. (2003) Acta Crystallogr. Sect. D Biol. Crystallogr. 59, 547-550), are encoded by two almost identical genes, with only the single substitution Asp for Asn at residue 62. Amidolytic assays indicated that they possess slightly different enzymatic properties. Crystal structures of A. actus venom serine proteinases I and II were determined at resolution of 2.0 and 2.1 A with the identification of trisaccharide (NAG(301)-FUC(302)-NAG(303)) and monosaccharide (NAG(301)) residues in them, respectively. The substrate binding sites S3 of the two proteinases appear much shallower than that of Trimeresurus stejnegeri venom plasminogen activator despite the overall structural similarity. Based on structural analysis, we showed that these Asn(35)-linked oligosaccharides collide spatially with some inhibitors, such as soybean trypsin inhibitor, and would therefore hinder their inhibitory binding. Difference of the carbohydrates in both the proteinases might also lead to their altered catalytic activities.
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Structural Biology, Chinese Academy of Sciences, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, The People's Republic of China.
authors.forename: Zhongliang
authors.initials: Z
authors.lastname: Zhu
authors.forename: Zhi
authors.initials: Z
authors.lastname: Liang
authors.forename: Tianyi
authors.initials: T
authors.lastname: Zhang
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Zhu
authors.forename: Weihua
authors.initials: W
authors.lastname: Xu
authors.forename: Maikun
authors.initials: M
authors.lastname: Teng
authors.forename: Liwen
authors.initials: L
authors.lastname: Niu
mesh_terms: D017836:Agkistrodon; D000595:Amino Acid Sequence; D000682:Amyloid; D000818:Animals; D001216:Asparagine / Q000737:chemistry; D001224:Aspartic Acid / Q000737:chemistry; D001483:Base Sequence; D001665:Binding Sites; D002241:Carbohydrates / Q000737:chemistry; D018360:Crystallography, X-Ray; D018076:DNA, Complementary / Q000378:metabolism; D006031:Glycosylation; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009005:Monosaccharides / Q000737:chemistry; D016297:Mutagenesis, Site-Directed; D009844:Oligosaccharides / Q000737:chemistry; D011487:Protein Conformation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D012697:Serine Endopeptidases / Q000737:chemistry*; D012910:Snake Venoms; D013045:Species Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D017841:Trimeresurus; D014357:Trypsin / Q000494:pharmacology; D014360:Trypsin Inhibitor, Kunitz Soybean / Q000494:pharmacology
chemical_list: D000682:Amyloid; D002241:Carbohydrates; D018076:DNA, Complementary; D009005:Monosaccharides; D009844:Oligosaccharides; D012910:Snake Venoms; D001224:Aspartic Acid; D001216:Asparagine; D014360:Trypsin Inhibitor, Kunitz Soybean; D012697:Serine Endopeptidases; D014357:Trypsin