title: Mutational analyses of Plasmodium falciparum and human S-adenosylhomocysteine hydrolases.
abstract: S-adenosylhomocysteine hydrolase is a prospective target for developing new anti-malarial drugs. Inhibition of the hydrolase results in an anti-cellular effect due to the suppression of adenosylmethionine-dependent transmethylations. Based on the crystal structure of Plasmodium falciparum S-adenosylhomocysteine hydrolase which we have determined recently, we performed mutational analyses on P. falciparum and human enzymes. Cys59 and Ala84 of the parasite enzyme, and the equivalent residues on the human enzyme, Thr60 and Gln85, were examined. Mutations of Cys59 and Thr60 caused dramatic impact on inhibition by 2-fluoronoraristeromycin without significant effect both on its kinetic parameters and on inhibition constant against noraristeromycin. In addition, the impact was independent from the electronegativity of the side chain of the substituting residue. These results showed that steric hindrance between a functional group at the 2-position of an adenine nucleoside inhibitor and Thr60 of the human enzyme, not an electrostatic effect, contributed to inhibitor selectivity.
authors: Department of Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
authors: Masayuki
authors: M
authors: Nakanishi
authors: Saori
authors: S
authors: Yabe
authors: Nobutada
authors: N
authors: Tanaka
authors: Yasutomo
authors: Y
authors: Ito
authors: Kazuo T
authors: KT
authors: Nakamura
authors: Yukio
authors: Y
authors: Kitade
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D043383:Adenosylhomocysteinase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D019943:Amino Acid Substitution; D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D016297:Mutagenesis, Site-Directed; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D055672:Static Electricity
chemical_list: C487476:2-fluoronoraristeromycin; D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; C030034:aristeromycin; D043383:Adenosylhomocysteinase; D000241:Adenosine