Nakatani H, Uehara Y, Hiromi K
J Biochem. 1975 Sep;78(3):611-6. doi: 10.1093/oxfordjournals.jbchem.a130947.
The interaction of benzeneboronic acid(BBA), a possible transition state analog, with subtilisin BPN' [EC 3.4.21.14] was studied by the temperature-jump method at various pH's, temperatures and in D2O as well as H2O. From analysis of the concentration dependence of the relaxation times, it was suggested that the subtillsin-BBA interactions consist of at least two elementary steps, a fast bimolecular association followed by a slow unimolecular process. Similar concentration dependence was observed at pH 6.1-6.7 at 25degrees. However, in D2O the reciprocal relaxation times generally decreased compared to those in H2O and became concentration-independent below pD 6.5. The relaxation times were influenced considerably by the temperature. From these results, the slow unimolecular process was assigned to the trigonal-tetrahedral interconversion of BBA at the active site of the enzyme.
采用温度跃变方法，在不同pH值、温度条件下，于重水（D₂O）和水（H₂O）中研究了苯硼酸（BBA，一种可能的过渡态类似物）与枯草杆菌蛋白酶BPN'[EC 3.4.21.14]的相互作用。通过分析弛豫时间的浓度依赖性，结果表明枯草杆菌蛋白酶与BBA的相互作用至少由两个基本步骤组成，即快速的双分子缔合，随后是缓慢的单分子过程。在25℃、pH 6.1 - 6.7条件下观察到类似的浓度依赖性。然而，在重水中，与在水中相比，弛豫时间的倒数通常降低，并且在pD 6.5以下变得与浓度无关。弛豫时间受温度影响很大。根据这些结果，将缓慢的单分子过程归因于BBA在酶活性位点的三角-四面体相互转化。
