Cryoenzymology: the study of enzyme mechanisms at subzero temperatures
Cryoenzymology: the study of enzyme mechanisms at subzero temperatures
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冷冻酶学：零下温度下酶机制的研究
DOI：
10.1021/ar50115a001
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发表时间：
1977
影响因子：
18.3
通讯作者：
A. Fink
中科院分区：
文献类型：
--
作者：
A. Fink
酶是非常有效的催化剂。通常发现，在相应的非催化反应中，速率提高了1012或更高，在类似的酸或碱催化反应中，速率提高了106-109。人们提出了许多因素来解释酶的催化效率，包括菌株，1,2结合熵，3酸碱催化，4与过渡态配合物的互补性，5以及邻近和取向效应。酶机制研究的一个主要目标是在催化的动态过程中阐明酶和底物之间相互作用的性质。实现这一目标的主要障碍是由于人们对这一目标的反应非常迅速。酶学家普遍认为，在底物与酶的活性位点（基本上以扩散控制的速率7）进行初始生产性结合后，会产生一系列中间体（eq 1）和过渡态复合物，最终导致产物和游离酶的释放。从本质上讲，问题归结为识别和描述这些中间状态和过渡状态。低温酶学的基础本报告涉及一种相对较新的研究酶机制的方法，即低温酶学，它具有克服上述问题的潜力。特别是，正如将要说明的那样，该方法非常适合于在原子分辨率上提供有关酶-底物中间体的结构信息，以及与此类中间体转化相关的动力学和热力学参数。我们目前对酶-底物相互作用细节的了解大多来自对假底物或抑制剂的研究。在这种情况下，极慢的反应速率似乎很可能是由于酶催化基团和底物的定向不正确，因此这些研究提供了误导性的信息。他于1943年出生于英国，在加拿大接受教育，并在安大略省金斯顿的女王大学获得学士和博士学位。随后，他花了一年半的时间做博士后
Enzymes are very efficient catalysts. Typically rate enhancements of 1012 or greater over the corresponding noncatalyzed reaction and of 106-109 in the analogous acid-or base-catalyzed reaction are found. 1 Many factors have been proposed to account for the efficiency of enzyme catalysis, 1 including strain, 1, 2 entropy of binding, 3 acid-base catalysis, 4 complementarity to the transition-state complex, 5 and proximity and orienta-tion effects. 6 A major goal in enzyme mechanism studies is the elucidation of the nature of the interaction between enzyme and substrate during the dynamic processes of the catalysis. The main obstacle to the achievement of this goal stems from thevery rapidity of the reaction which makes it of such interest. It is generally accepted by enzymologists that, after the initial productive binding of substrate to the active site of the enzyme (at an essentially diffusion-controlled rate7), a series of intermediates (eq 1) and transition-state complexes occur, leading to the eventual release of products and free enzyme. In essence, the problem reduces to one of identifying and characterizing these intermediates and transition states. Underlying Basis of Cryoenzymology This Account concerns a relatively new approach for investigating enzyme mechanisms, namely cryoenzy-mology, 8 which possesses the potential to overcome the above-mentioned problem. In particular, as will be illustrated, the method is well-suited for the provision of structural informationabout enzyme-substrate intermediates at atomic resolution, as well as kinetic and thermodynamic parametersassociated with such intermediate transformations. Most of our current in-sights into the details of enzyme-substrate interactions have come from studies with pseudosubstrates or in-hibitors. 9 It seems probable that in such cases the very slow rate of reaction is due to improper orientation of enzyme catalytic groups and the substrate, and con-sequently such studies provide misleading informationTony Fink is anAssociate Professor of Chemistry at the University of California, Santa Cruz. He was born in England in 1943 and educated in Canada, where he received his B. Sc. and Ph. D. degreesfrom Queen's University, Kingston, Ontario. He subsequently spent a year and a half as a postdoctoral fellow with