Structural basis for flip-flop action of thiamin pyrophosphate-dependent enzymes revealed by human pyruvate dehydrogenase
Structural basis for flip-flop action of thiamin pyrophosphate-dependent enzymes revealed by human pyruvate dehydrogenase
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DOI：
10.1074/jbc.m300339200
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发表时间：
2003-06-06
影响因子：
4.8
通讯作者：
Patel, MS
中科院分区：
文献类型：
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作者：
Ciszak, EM;Korotchkina, LG;Patel, MS
维生素B1的衍生物，焦磷酸硫胺素，是在能量产生途径中进行催化的酶的辅因子。在α（2）β（2）-异四聚体人丙酮酸脱氢酶中，该辅因子用于切割丙酮酸的C-alpha-C（=O）键，然后还原性乙酰转移至硫辛酰-二氢硫辛酰胺乙酰转移酶。两个在化学上等价的催化位点的动态不等价性还没有被理解。为了了解这种酶的作用机制，我们在1.95埃分辨率下测定了人丙酮酸脱氢酶的完整形式的晶体结构。我们提出了一个模型的触发器行动，这种酶通过协调类似2埃梭状运动的异源二聚体。焦磷酸硫胺素结合在人类丙酮酸脱氢酶与功能相关的酶的相似性表明，这种新定义的穿梭样运动的结构域是常见的焦磷酸硫胺素依赖性酶的家庭。
The derivative of vitamin B1, thiamin pyrophosphate, is a cofactor of enzymes performing catalysis in pathways of energy production. In alpha(2)beta(2)-heterotetrameric human pyruvate dehydrogenase, this cofactor is used to cleave the C-alpha-C(=O) bond of pyruvate followed by reductive acetyl transfer to lipoyl-dihydrolipoamide acetyltransferase. The dynamic nonequivalence of two, otherwise chemically equivalent, catalytic sites has not yet been understood. To understand the mechanism of action of this enzyme, we determined the crystal structure of the holo-form of human pyruvate dehydrogenase at 1.95-Angstrom resolution. We propose a model for the flip-flop action of this enzyme through a concerted similar to2-Angstrom shuttle-like motion of its heterodimers. Similarity of thiamin pyrophosphate binding in human pyruvate dehydrogenase with functionally related enzymes suggests that this newly defined shuttle-like motion of domains is common to the family of thiamin pyrophosphate-dependent enzymes.