title: Effects of metal ions and disulfide bonds on the activity of phosphodiesterase from Trimeresurus stejnegeri venom.
abstract: Obviously different from the other known phosphodiesterases, the phosphodiesterase from Trimeresurus stejnegeri venom (TS-PDE) consists of two different chains linked with disulfide bonds and contains both endogenous Cu(2+) and Zn(2+). Cu(2+) and Zn(2+) are important for its phosphodiesterase activity. In this study, the effects of metal ions and small-molecule reductants on its structure and activity have been investigated by polyacrylamide gel electrophoresis, high performance liquid chromatography, fluorescence and electron paramagnetic resonance spectroscopy. The results show that TS-PDE has one class of Zn(2+) binding site and two classes of Cu(2+) binding site, including the high affinity activator sites and the low affinity sites. Cu(2+) ions function as a switch for its phosphodiesterase activity. The catalytic activity of TS-PDE does not have an absolute requirement for Cu(2+) and Zn(2+). Mg(2+), Mn(2+), Ni(2+), Co(2+) and Ca(2+) are all effective for its phosphodiesterase activity. TS-PDE has seven disulfide bonds and ten free cysteine residues. l-Ascorbate inhibits the phosphodiesterase activity of TS-PDE through reduction of the Cu(2+), while dithiothreitol, glutathione and tris(2-carboxyethyl)phosphine inhibit the phosphodiesterase activity of TS-PDE by reducing both the Cu(2+) and disulfide bonds. The catalytic activity of TS-PDE relies on its disulfide bonds and bimetallic cluster. In addition, biologically-relevant reductants, glutathione and l-ascorbate, have been found to be endogenous inhibitors to the phosphodiesterase activity of TS-PDE.
authors.affiliation: Department of Chemistry, University of Science and Technology of China, Hefei, P. R. China.
authors.forename: Lili
authors.initials: L
authors.lastname: Peng
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Xu
authors.forename: Mingchun
authors.initials: M
authors.lastname: Guo
authors.forename: Xincheng
authors.initials: X
authors.lastname: Yan
authors.forename: Shasha
authors.initials: S
authors.lastname: Wang
authors.forename: Shang
authors.initials: S
authors.lastname: Gao
authors.forename: Shanshan
authors.initials: S
authors.lastname: Zhu
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003435:Crotalid Venoms / Q000201:enzymology*; D004220:Disulfides / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D004591:Electrophoresis, Polyacrylamide Gel; D008670:Metals / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010727:Phosphoric Diester Hydrolases / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D003435:Crotalid Venoms; D004220:Disulfides; D008670:Metals; C029748:Trimeresurus venoms; D010727:Phosphoric Diester Hydrolases