叶绿体偶联因子 1 紧密核苷酸结合位点对 ADP 和 ATP 亲和力的 pH 依赖性变化。

pH dependent changes in ADP and ATP affinity for the tight nucleotide-binding site of chloroplast coupling factor 1.

机构信息

The Institute of Soil Science and Photosynthesis, Academy of Science of the USSR, Pushchino, Moscow Region, USSR.

出版信息

Photosynth Res. 1990 Jul;25(1):11-6. doi: 10.1007/BF00051731.

PMID:24420166

Abstract

The pH-dependence of ADP and ATP affinity for CF1 tight nucleotide-binding sites was studied under conditions of equilibrium between bound and free labeled nucleotides. With the nucleotide/CF1 ratio>1, the ATP content in tightly bound nucleotides depended only slightly on medium pH. With the nucleotide/CF1 ratio approaching 1, tightly bound ATP content grew rapidly with decreasing pH. Calculations of ADP/ATP ratio in free and tightly bound nucleotides showed that decreasing the pH from 8.0 to 6.0 induced a 150 times greater affinity of the nucleotide-binding site for ATP than for ADP. The data indicates that ATP-ADP equilibrium at the CF1 tight nucleotide-binding site depends on protonation of specific acid-base groups of the enzyme.

摘要

在结合态和游离态标记核苷酸达到平衡的条件下，研究了 ADP 和 ATP 与 CF1 紧密核苷酸结合位点亲和力对 pH 的依赖性。当核苷酸/CF1 比值>1 时，紧密结合核苷酸中的 ATP 含量仅略微依赖于介质 pH。当核苷酸/CF1 比值接近 1 时，随着 pH 的降低，紧密结合的 ATP 含量迅速增加。对游离和紧密结合核苷酸中 ADP/ATP 比值的计算表明，将 pH 从 8.0 降低至 6.0 会导致核苷酸结合位点对 ATP 的亲和力比 ADP 高 150 倍。这些数据表明，CF1 紧密核苷酸结合位点的 ATP-ADP 平衡取决于酶的特定酸碱基团的质子化。