Specificity of pyridinium inhibitors of the ubiquinone reduction sites in mitochondrial complex I.
Dual binding sites for pyridinium-type inhibitors in bovine heart mitochondrial complex I have been proposed (Gluck, M. R., Krueger, M. J., Ramsay, R. R., Sablin, S. O., Singer, T. P., and Nicklas, W. J. (1994) J. Biol. Chem. 269, 3167-3174). The marked biphasic nature of the dose-response curve for inhibition of the enzyme by MP-6(N-methyl-4-[2-(p-tert-butylbenzyl)propyl]pyridinium) makes this compound the first selective inhibitor of the two sites (Miyoshi, H., Inoue, M., Okamoto, S., Ohshima, M., Sakamoto, K., and Iwamura, H. (1997) J. Biol. Chem. 272, 16176-16183). Modifications of the structure of MP-6 show that a tert-butyl group on the benzene ring, a methyl group attached to the pyridine nitrogen atom, para-substitution pattern in the pyridine ring, and the presence of a branched structure in the spacer moiety are important for the selective inhibition. On the basis of the structural specificity, we synthesized a selective inhibitor, MP-24 (N-methyl-4-[2-methyl-2-(p-tert-butylbenzyl)propyl]pyridinium), which elicits greater selectivity. Characterization of the inhibitory behavior of MP-24 provided further strong evidence for the dual binding sites model.
Miyoshi
H
H
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. miyoshi@kais.kyoto-u.ac.jp
Iwata
J
J
Sakamoto
K
K
Furukawa
H
H
Takada
M
M
Iwamura
H
H
Watanabe
T
T
Kodama
Y
Y
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000201:enzymology; D015394:Molecular Structure; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010084:Oxidation-Reduction; D011726:Pyridinium Compounds / Q000737:chemistry / Q000494:pharmacology*; D014451:Ubiquinone / Q000378:metabolism*
D004791:Enzyme Inhibitors; C113429:N-methyl-4-(2-(4-tert-butylbenzyl)propyl)pyridinium; C113430:N-methyl-4-(2-methyl-2-(4-tert-butylbenzyl)propyl)pyridinium; D011726:Pyridinium Compounds; D014451:Ubiquinone; D016660:NAD(P)H Dehydrogenase (Quinone)