Usmanov R A, Neef H, Pustynnikov M G, Schellenberger A, Kochetov G A
Biochem Int. 1985 Mar;10(3):479-86.
The coenzyme function of TPP analogues: 4'-NH-methyl-TPP,6'-methyl-TPP and 6'-methyl-4-nor-TPP has been studied in a transketolase-catalyzed reaction. Their dissociation constants have been found with the aid of the circular dichroism method, and coenzyme activity has been determined in a complete transketolase reaction, involving the substrate-donor and the substrate-acceptor, and also at the intermediate stage (by the alpha-carbanionic intermediate oxidation rate). The coenzyme activity values have been found different and largely dependend on the nature of the substrates used. A possibility of TPP functioning by the "two-center mechanism" in a transketolase-catalyzed reaction is discussed.
硫胺素焦磷酸（TPP）类似物：4'-NH-甲基-TPP、6'-甲基-TPP和6'-甲基-4-去甲-TPP的辅酶功能已在转酮醇酶催化反应中进行了研究。借助圆二色性方法测定了它们的解离常数，并在完整的转酮醇酶反应中测定了辅酶活性，该反应涉及底物供体和底物受体，同时也在中间阶段（通过α-碳负离子中间体氧化速率）进行了测定。已发现辅酶活性值各不相同，且在很大程度上取决于所用底物的性质。文中讨论了TPP在转酮醇酶催化反应中通过“双中心机制”发挥作用的可能性。
