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Transition-state analysis of nucleoside hydrolase from Crithidia fasciculata


, : Transition-state analysis of nucleoside hydrolase from Crithidia fasciculata. Biochemistry, 3044: 10788-10795

The transition state of nucleoside hydrolase from the trypanosome Crithidia fasciculata has been characterized by multiple Vmax/Km kinetic isotope effects with labeled inosine and adenosine as substrates. Nucleoside hydrolase catalyzes the hydrolysis of the N-glycosidic linkage of the commonly occurring purine and pyrimidine nucleosides, with Vmax/Km ranging over 2 orders of magnitude. The kinetic isotope effects for inosine were [1'-3H] = 1.150 +/- 0.006, [2'-3H] = 1.161 +/- 0.003, [1'-14C] = 1.044 +/- 0.004, [9-15N] = 1.026 +/- 0.004, [4'-3H] = 0.992 +/- 0.003, and [5'-3H] = 1.051 +/- 0.003. The magnitude of the kinetic isotope effects for inosine, an equivalent [1'-3H] kinetic isotope effect for the poor substrate adenosine, and the rapid equilibrium random kinetic mechanism [Parkin D, W., Horenstein, B. A., Abdulah, D. R., Estupiñán, B., & Schramm, V. L. (1991) J. Biol. Chem. (in press)] all indicate that the isotope effects are fully expressed. The kinetic and solvent deuterium isotope effects have been used to analyze the transition-state structure using bond energy bond order vibrational analysis. The transition state involves a protonated hypoxanthine leaving group with a C-N glycosidic bond elongated to approximately 2 A. The ribose group contains substantial carbocationic character, unusually strong hyperconjugation of H2', and a bond length of approximately 3 A to the incoming oxygen nucleophile. The remote isotope effect (4'-3H and 5'-3H) and the results of transition-state calculations provide the most detailed description of the steric and bonding properties of an enzyme-stabilized transition state.

US$19.90

PMID: 1931998

DOI: 10.1021/bi00108a026


Other references

Dostal, H.; Wilcox, G., 1972: Ethrel application to tomatoes. HO Purdue University Cooperative Extension Service: 972 (69)

Nakamura, T.; Torimura, T.; Sakamoto, M.; Hashimoto, O.; Taniguchi, E.; Inoue, K.; Sakata, R.; Kumashiro, R.; Murohara, T.; Ueno, T.; Sata, M., 2007: Significance and therapeutic potential of endothelial progenitor cell transplantation in a cirrhotic liver rat model. Background & Aims: We investigated whether endothelial progenitor cell (EPC) transplantation could reduce established liver fibrosis and promote hepatic regeneration by isolating rat EPCs from bone marrow cells. Methods: Recipient rats were injec...

Davis S.M.; Tress B.M.; Hopper J.L.; Kaye A.H.; Rossiter S.C., 1987: Dynamic ct brain scanning in the hemodynamic evaluation of cerebral arterial occlusive disease. Dynamic cerebral CT scanning (DCT) was used to quantitatively analyse the haemodynamic effects of extracranial and intracranial arterial occlusive lesions in 17 patients with TIA's or minor cerebral infarcts. Using DCT and gamma variate curve...

Fernández Gil, M.; Izquierdo Villarroya, B.; Cassinello Ogea, C.; Cotera Usúa, I.; Abengochea Beisty, J.M., 2009: Valve replacement in a man with Chagas disease: anesthetic considerations. Revista Espanola de Anestesiologia Y Reanimacion 56(4): 262-265

Pinheiro, C.E.; Bezerra, A.C.; de Carvalho, J.C.; Araujo, O.M., 1981: Influence of vasodilator drugs on the incidence of dental caries in rats. Arquivos do Centro de Estudos Da Faculdade de Odontologia Da U. F. M. G 18(1-2): 25-29

Lovholt Finn; Harbitz Carl B.; Haugen Kjetil Braathen, 2005: A parametric study of tsunamis generated by submarine slides in the Ormen Lange/ Storegga area off western Norway. Tsunami generation by submarine slides have been a major concern in the risk assessment for the Ormen Lange gas field off Western Norway. Tsunamis are analysed with a numerical model supplemented by an analytical one. Both models show how slide ex...

Osman, A.A.; Govender, S., 1992: Traumatic dislocation of the lumbar spine at two levels. Injury 23(4): 277-278

Xue, Y.; Li, A.; Wang, L.; Feng, H.; Yao, X., 2006: PPSP: prediction of PK-specific phosphorylation site with Bayesian decision theory. Background: As a reversible and dynamic post-translational modification (PTM) of proteins, phosphorylation plays essential regulatory roles in a broad spectrum of the biological processes. Although many studies have been contributed on the molecul...

Taylor T.H.; Howard D.; Wills J.K.; Templeton W.C.Jr, 1971: Grass m establishment on bulldozed hill land in owen county kentucky. University of Kentucky Cooperative Extension Service Miscellaneous 394:

Hur, M-Wook.; Laney, J.D.; Jeon, S-Hack.; Ali, J.; Biggin, M.D., 2002: Zeste maintains repression of Ubx transgenes: support for a new model of Polycomb repression. During late embryogenesis, the expression domains of homeotic genes are maintained by two groups of ubiquitously expressed regulators: the Polycomb repressors and the Trithorax activators. It is not known how the activities of the two maintenance...