pH dependence of the thermal unfolding of ribonuclease A.
pH dependence of the thermal unfolding of ribonuclease A.
复制标题
核糖核酸酶 A 热解折叠的 pH 依赖性。
DOI：
10.1021/bi00755a029
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发表时间：
1972
期刊：
影响因子：
2.9
通讯作者：
P. Mcphie
中科院分区：
文献类型：
--
作者：
P. Mcphie
材料和方法。慢速 T 形跳跃实验是在先前描述的装置中进行的（Tsong 等人，1972）。动力学实验和差异光谱在 Cary 15 分光光度计中记录。平衡熔解曲线在配有热垫片的 Beckman DU 分光光度计中进行。“pH 跳跃”实验使用 Crothers (1964) 描述的类型的“加法器混合器”进行。 pH值使用Radiometer pH计26和GK-2321-C组合电极测量。核糖核酸酶 A (RASE) 获自 Worthington Bio-chemical Corp.。使用 278 nm 处的 9.8 X 103 摩尔吸光度测量蛋白质浓度。所有其他试剂均为分析级。 t 来自美国国立卫生研究院关节炎和代谢疾病研究所，马里兰州贝塞斯达，20014 年。收到于 1971 年 9 月 10 日。已知的蛋白质滴定曲线。第二个模型假设速率常数的 pH 依赖性主要源于天然和未折叠蛋白质滴定曲线的差异，这是由 Linderstrom-Lang 静电相互作用参数 w 的变化引起的，w 已知是球状蛋白质的构象和水合的函数。
Materials and Methods. Slow T-jump experiments were per-formed in the apparatus described previously (Tsong et al., 1972). Kinetic experiments and difference spectra were re-corded in a Cary 15 spectrophotometer. Equilibrium melting curves were performed in a Beckman DU spectrophotometer, equipped with thermospacers.“pH-jump” experiments were carried out using an “adder-mixer” of the type described by Crothers (1964). pH values were measured with a Radiometer pH meter 26, using a GK-2321-C combined electrode. Ribo-nuclease A (RASE) was obtained from the Worthington Bio-chemical Corp. Concentrations of protein were measured us-ing a molar absorbance of 9.8 X 103 at 278 nm. All other re-agents were analytical grade. t From the National Institute of Arthritis and Metabolic Diseases, National Institutes of Health, Bethesda, Maryland 20014. Received September 10, 1971. known titration curve of the protein. Thesecond model postu-lates that the pH dependence of the rate constants arises mainly from differences in the titration curves of the native and unfolded protein, caused by changes in the Linderstrom-Lang electrostatic interaction parameter, w, which is known to be a function of the conformation and hydration of globular proteins.