Equilibrium dialysis study and mechanistic implications of coenzyme A binding to acetyl-CoA synthase/carbon monoxide dehydrogenase from Clostridium thermoaceticum.
Equilibrium dialysis study and mechanistic implications of coenzyme A binding to acetyl-CoA synthase/carbon monoxide dehydrogenase from Clostridium thermoaceticum.
复制标题
平衡透析研究以及辅酶 A 与热乙酸梭菌乙酰辅酶 A 合酶/一氧化碳脱氢酶结合的机制意义。
DOI：
10.1007/s007750050346
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Lindahl,PA
中科院分区：
文献类型：
--
作者：
Wilson,BE;Lindahl,PA
Clostridiumthermoaceticumwere determined by equilibrium dialysis. CoA bound to as-isolated nativeα2β2enzyme withKD= 10 ± 8 μM andn= 0.2 ± 0.1 moles perαβdimer, whereKDis the thermodynamic dissociation constant andnis the number of CoAs bound perαβdimer of the enzyme. The enzyme is heterogeneous; for example, only ∼ 30% ofαsubunits contain A-clusters with labile Ni ions (the remainder have nonlabile Ni ions and are nonfunctional). The observednvalue suggests that CoA binds only toαβunits with Ni-labile A-clusters. The CoA binding properties of enzyme lacking labile Ni was essentially the same, indicating that CoA does not bind directly to the Ni of the A-cluster. This was further evidenced by the observation that bound CoA did not inhibit removal of the labile Ni by 1,10-phenanthroline. CoA did not bind CO-reduced enzyme, and the EPR signal exhibited by the one-electron reduced and CO-bound form of the A-cluster was unaffected by the presence of up to 200 μM CoA. In contrast, CoA did bind Ti(III)-citrate-reduced enzyme (KD= 36 ± 16 μM,n= 0.16 ± 0.08). Implications of these results for the mechanism of catalysis are discussed.
