Yeast squalene synthase. A mechanism for addition of substrates and activation by NADPH.
作者： K.A. Mookhtiar , S.S. Kalinowski , D. Zhang , C.D. Poulter
DOI: 10.1016/S0021-9258(19)78111-3
关键词: Enzyme activator 、 Farnesyl-diphosphate farnesyltransferase 、 Squalene 、 Substrate (chemistry) 、 Enzyme 、 Biochemistry 、 Cofactor 、 Mechanism of action 、 Stereochemistry 、 ATP synthase 、 Chemistry
摘要: Squalene synthase catalyzes the condensation of two molecules farnesyl diphosphate (FPP) to give presqualene (PSPP) and subsequent reductive rearrangement PSPP squalene. Previous studies mechanism addition FPP enzyme have led conflicting interpretations initial velocity measurements (Beytia, E., Qureshi, A. A., Porter, J.W. (1973) J. Biol. Chem. 248, 1856-1867; Agnew, W.S., Popjak, G. (1978) 253, 4566-4573). Initial velocities for synthesis squalene were measured over a wider range NADPH concentrations than previously reported, using soluble form recombinant enzyme. In absence NADPH, formation was activated by at above approximately 0.5 microM. At fixed levels dependence rates on indicated that C15 substrate added sequential mechanism. addition, stimulated 40-fold saturating cofactor. This stimulation is, least in part, reduction
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