60(P-39) ファルネシル二リン酸合成酵素の反応機構解明のためのアプローチ(ポスター発表の部)

概要

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Farnesyl diphosphate (FPP, C_<15>) synthase (FPS) catalyzes the sequential "1'-4 condensation" of isopentenyl diphosphate (IPP, C_5) with dimethylallyl diphosphate (DMAPP) as a primer via geranyl diphosphate to give FPP in the biosynthesis of short prenyl products. On this enzymatic reaction, two mechanisms have been presented: two-step mechanism of "trans-addition-trans-elimination" advocated by Cornforth et al. and "ionization-condensation-elimination" advocated by Poulter et al. In order to elucidate the mechanism of FPS reaction, we examined the reactivity of (R/S)-1-methylgeranyl diphosphate as an artificial substrate with IPP by use of Bacillus stearothermophilus FPS. The configurations of the esters derived by the reaction using 1-methylgeranyl diphosphate with S-2-methoxy-2-(1-naphthyl)propionic acid (S-MαNP acid) were determined by the difference in the chemical shift according to the sector rule. The relative yield of the products that derived the enzymatic reaction of chiral 1-methylgeranyl diphosphate with IPP was found to be R/S=5/4, indicating that the enzymatic condensation proceeded with S_N-1 type substitution via formation of cation by ionization-condensation-elimination mechanism.
天然有機化合物討論会の論文
2004-10-01