糖原颗粒中与磷酸化酶瞬时激活相关的构象变化。使用活性、电子自旋共振和磷核磁共振测量的研究。

Conformational changes associated with transient activation of phosphorylase in glycogen particles. Studies using activity, electron-spin-resonance and phosphorus-nuclear-magnetic-resonance measurements.

Busby S J, Gadian D G, Griffiths J R, Radda G K, Richards R E

Eur J Biochem. 1976 Mar 16;63(1):23-31. doi: 10.1111/j.1432-1033.1976.tb10202.x.

Abstract

Calcium-dependent transient phosphorylation of phorphorylase b has been monitored in a rabbit muscle glycogen particle fraction. Using a phosphorus nuclear magnetic resonance assay, the changes in concentrations of small phosphate-containing metabolites associated with this event have been measured. In addition, the conformation of phosphorylase has been monitored during transient activation by observing changes in the electron spin resonance signal from added spin-labelled phosphorylase. 2. The transient activation was associated with a loss of glucose-6-phosphate from phosphorylase b; newly formed phosphorylase a binds the nucleotides ADP, AMP, or IMP. Because of the fast interconversion of these nucleotides the species bound to phosphorylase a change throughout the process. 3. Lowering the [Mg2+] : [Ca2+] ratio during transient activation causes accumulation of ADP. Electron spin resonance data from spin-labelled phosphorylase shows that, under these conditions, ADP binding to phosphorylase a is potentiated. 4. Calcium-dependent activation in the glycogen particle fraction is compared to the activation of phosphorylase in vivo.

摘要

已在兔肌肉糖原颗粒组分中监测了磷酸化酶b的钙依赖性瞬时磷酸化。使用磷核磁共振测定法，测量了与此事件相关的含小磷酸盐代谢物浓度的变化。此外，通过观察添加的自旋标记磷酸化酶的电子自旋共振信号的变化，在瞬时激活过程中监测了磷酸化酶的构象。2. 瞬时激活与磷酸化酶b中葡萄糖-6-磷酸的丢失有关；新形成的磷酸化酶a结合核苷酸ADP、AMP或IMP。由于这些核苷酸的快速相互转化，整个过程中与磷酸化酶a结合的种类会发生变化。3. 在瞬时激活过程中降低[Mg2+]：[Ca2+]比值会导致ADP积累。来自自旋标记磷酸化酶的电子自旋共振数据表明，在这些条件下，ADP与磷酸化酶a的结合增强。4. 将糖原颗粒组分中的钙依赖性激活与体内磷酸化酶的激活进行了比较。