Zhou G Q, Zhong W Z
Eur J Biochem. 1982 Nov 15;128(2-3):383-7.
In the study of enzyme-catalysed mechanisms, it is often necessary to calculate the upper limit of enzyme reaction, which is usually used as an important criterion to identify whether an assumed enzyme-catalysed mechanism is reasonable or not. Basically, in the existing methods, there are two kinds of models, the Alberty-Hammes-Eigen model and the Chou model, for calculating the upper limit of enzyme reaction. In this paper, an analysis and comparison between these two models are made. It is pointed out that the magnitude of the van der Waals' binding energy between enzyme and substrate molecules will play a key role in deciding whether there is a significant difference or not for the results calculated from these two models. Through such a comparison, the role of the major protein outside the active site of an enzyme molecule also becomes obvious; if the van der Waals' binding energy is very small, the major protein will act like a 'wall', blocking the flow of some substrate molecules to the active site; while if the van der Waals' energy is greater than 3 kT (where k is the Boltzmann constant and T the absolute temperature), the major protein will behave like a 'accelerator', speeding up the flow of the substrate molecules to the active site around the enzyme molecule.
在酶催化机制的研究中，常常需要计算酶反应的上限，这通常被用作判断所假设的酶催化机制是否合理的重要标准。基本上，在现有方法中，有两种模型，即阿尔贝蒂 - 哈姆斯 - 艾根模型和周模型，用于计算酶反应的上限。本文对这两种模型进行了分析和比较。指出酶与底物分子之间范德华结合能的大小在决定这两种模型计算结果是否存在显著差异方面将起关键作用。通过这样的比较，酶分子活性位点之外主要蛋白质的作用也变得明显；如果范德华结合能非常小，主要蛋白质将起到“壁”的作用，阻止一些底物分子流向活性位点；而如果范德华能大于3kT（其中k是玻尔兹曼常数，T是绝对温度），主要蛋白质将起到“加速器”的作用，加速底物分子流向酶分子周围的活性位点。
