Phosphorus-31 nuclear magnetic resonance studies of the binding of oxidized coenzymes to Lactobacillus casei dihydrofolate reductase.
Phosphorus-31 nuclear magnetic resonance studies of the binding of oxidized coenzymes to Lactobacillus casei dihydrofolate reductase.
复制标题
氧化辅酶与干酪乳杆菌二氢叶酸还原酶结合的 Phosphorus-31 核磁共振研究。
作者：
E. Hyde;B. Birdsall;G. Roberts;J. Feeney;A. Burgen
NADP+及其结构类似物与干酪乳杆菌二氢叶酸还原酶的二元和三元复合物的~（31）P NMR谱已获得。在所有情况下，2 '-磷酸共振向低场移动2.7-2.9 ppm。线形分析这种共振作为辅酶浓度的函数给出了许多复合物的辅酶的解离速率常数的值。所获得的值进行了讨论辅酶结合的动力学机制。焦磷酸盐共振的化学位移在3.8 ppm的范围内从一个复合物到另一个复合物而变化。这些信号的个人焦磷酸31 P核和化学位移变化的结构起源的分配进行了讨论。根据这些数据和在前面的论文[Hyde，E.一、Birdsall，B.，罗伯茨，G。C. K.，Feeney，J.，& Burgen，A. S. V.（1980）Biochemistry（本期四篇论文中的第三篇）]，得出的结论是硫代烟酰胺和乙酰吡啶辅酶类似物的“烟酰胺”末端与酶的结合与天然辅酶NADP+的结合完全不同。
The 31P NMR spectra of NADP+ and a number of its structural analogues have been obtained from their binary and ternary complexes with Lactobacillus casei dihydrofolate reductase. The 2'-phosphate resonance is shifted downfield 2.7-2.9 ppm in all cases. Line-shape analysis of this resonance as a function of coenzyme concentration gave values for the dissociation rate constant of the coenzyme from many of the complexes. The values obtained are discussed in terms of the kinetic mechanism of coenzyme binding. The chemical shifts of the pyrophosphate resonances vary from one complex to another over a range of 3.8 ppm. The assignment of these signals to the individuals pyrophosphate 31P nuclei and the structural origins of the chemical shift changes are discussed. From these data, and the 1H NMR experiments describedin the preceding paper [Hyde, E. I., Birdsall, B., Roberts, G. C. K., Feeney, J., & Burgen, A. S. V. (1980) Biochemistry (third paper of four in this issue)], it is concluded that the "nicotinamide" end of the thionicotinamide and acetylpyridine coenzyme analogue binds to the enzyme quite differently from that of the natural coenzyme NADP+.