title: Purification and partial characterization of a novel phosphodiesterase from the venom of Trimeresurus stejnegeri: inhibition of platelet aggregation.
abstract: The phosphodiesterases (PDEs) are a superfamily of enzymes that have multiple roles in extracellular nucleotide metabolism and in the regulation of nucleotide-based intercellular signaling. Here we describe for the first time the isolation and partial characterization of a novel phosphodiesterase from Trimeresurus stejnegeri venom, named TS-PDE, using ion exchange and gel filtration chromatography. The purified TS-PDE is shown to be homogeneous as judged by SDS-PAGE and capillary isoelectric focusing. TS-PDE is a glycoprotein which contains 2.48% carbohydrate. Unlike other PDEs which are usually single polypeptide chain proteins with isoelectric points between 7.5 and 10.5, TS-PDE is a disulfide-linked heterodimer with an isoelectric point of 5.1 and a molecular mass of 100 kDa. The N-terminal amino acids of two chains are valine and serine, respectively. Furthermore, among all identified PDEs, only TS-PDE contains both of endogenous Cu(2+) and Zn(2+) which are essential for its phosphodiesterase activity. The purified TS-PDE exhibits broad phosphodiesterase substrate range with the order of specificity: nicotinamide guanine dinucleotide > ATP > nicotinamide adenine dinucleotide > ADP. The purified TS-PDE shows an exonuclease activity and no contamination with either alkaline phosphatase or 5'-nucleotidase activity. TS-PDE strongly inhibits ADP-induced platelet aggregation in human platelet-rich plasma by hydrolyzing ADP. Altogether, these results indicate that the novel TS-PDE is a unique phosphodiesterase with different structure from the known PDEs.
authors.affiliation: Department of Chemistry, University of Science and Technology of China, No. 96, Jinzhai Road, Hefei, Anhui 230026, PR China.
authors.forename: Lili
authors.initials: L
authors.lastname: Peng
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Xu
authors.forename: Dengke
authors.initials: D
authors.lastname: Shen
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jiajia
authors.initials: J
authors.lastname: Song
authors.forename: Xincheng
authors.initials: X
authors.lastname: Yan
authors.forename: Mingchun
authors.initials: M
authors.lastname: Guo
mesh_terms: D015720:5'-Nucleotidase / Q000737:chemistry; D000818:Animals; D003300:Copper / Q000737:chemistry; D003435:Crotalid Venoms / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007700:Kinetics; D008970:Molecular Weight; D009532:Nickel / Q000737:chemistry; D010727:Phosphoric Diester Hydrolases / Q000737:chemistry* / Q000302:isolation & purification; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000737:chemistry* / Q000302:isolation & purification; D017841:Trimeresurus / Q000378:metabolism*
chemical_list: D003435:Crotalid Venoms; D010975:Platelet Aggregation Inhibitors; D003300:Copper; D009532:Nickel; D015720:5'-Nucleotidase; D010727:Phosphoric Diester Hydrolases