Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA.
Bioorg Chem. 2012 Aug;43:26-36. doi: 10.1016/j.bioorg.2011.12.001. Epub 2011 Dec 30.
Thiamin diphosphate (ThDP) is the biologically active form of vitamin B(1), and ThDP-dependent enzymes are found in all forms of life. The catalytic mechanism of this family requires the formation of a common intermediate, the 2α-carbanion-enamine, regardless of whether the enzyme is involved in C-C bond formation or breakdown, or even formation of C-N, C-O and C-S bonds. This demands that the enzymes must screen substrates prior to, and/or after, formation of the common intermediate. This review is focused on the group for which the second step is the protonation of the 2α-carbanion, i.e., the ThDP-dependent decarboxylases. Based on kinetic data, sequence/structure alignments and mutagenesis studies the factors involved in substrate specificity have been identified.
硫胺素焦磷酸（ThDP）是维生素 B(1) 的生物活性形式，而依赖 ThDP 的酶存在于所有生命形式中。该酶家族的催化机制需要形成一个共同的中间体，即 2α-碳负离子-烯胺，无论该酶是否参与 C-C 键的形成或断裂，甚至是 C-N、C-O 和 C-S 键的形成。这就要求酶必须在共同中间体形成之前和/或之后筛选底物。这篇综述主要针对第二步是 2α-碳负离子质子化的酶，即依赖 ThDP 的脱羧酶。基于动力学数据、序列/结构比对和突变研究，已经确定了参与底物特异性的因素。
