Trentham D R
Biochem J. 1971 Mar;122(1):59-69. doi: 10.1042/bj1220059.
Transient kinetic methods have been used to study the influence of NAD(+) on the rate of elementary processes of the reversible oxidative phosphorylation of d-glyceraldehyde 3-phosphate catalysed by d-glyceraldehyde 3-phosphate dehydrogenase. In the pH range 5-8 NAD(+) is bound to the enzyme during the following elementary processes of the mechanism: phosphorolysis of the acyl-enzyme, its formation from 1,3-diphosphoglycerate and the enzyme and the formation and breakdown of the glyceraldehyde 3-phosphate-enzyme complex. The rates of these four elementary processes only equal or exceed the turnover rate of the enzyme when NAD(+) is bound and are as much as 10(4) times the rates in the absence of NAD(+). Autocatalysis of the reductive dephosphorylation of 1,3-diphosphoglycerate occurs when glyceraldehyde 3-phosphate release is rate determining because NAD(+) is a reaction product. An important feature of the enzyme mechanism is that the negative-free-energy change of a chemical reaction, acyl-enzyme formation, is linked in a simple way to the positive-free-energy change of a dissociation reaction, NAD(+) release.
瞬态动力学方法已被用于研究NAD⁺对由3-磷酸甘油醛脱氢酶催化的3-磷酸甘油醛可逆氧化磷酸化基本过程速率的影响。在pH值5 - 8范围内，NAD⁺在该机制的以下基本过程中与酶结合：酰基酶的磷酸解、由1,3 - 二磷酸甘油酸和酶形成酰基酶以及3-磷酸甘油醛 - 酶复合物的形成和分解。当NAD⁺结合时，这四个基本过程的速率才等于或超过酶的周转速率，并且比不存在NAD⁺时的速率高多达10⁴倍。当3-磷酸甘油醛的释放是速率决定因素时，由于NAD⁺是反应产物，会发生1,3 - 二磷酸甘油酸还原脱磷酸化的自催化作用。该酶机制的一个重要特征是，化学反应（酰基酶形成）的负自由能变化以一种简单的方式与解离反应（NAD⁺释放）的正自由能变化相关联。
