小牛脑微管体外重组的热容量微量热法

Heat capacity microcalorimetry of the in vitro reconstitution of calf brain microtubules.

作者信息

Hinz H J, Gorbunoff M J, Price B, Timasheff S N

出版信息

Biochemistry. 1979 Jul 10;18(14):3084-9. doi: 10.1021/bi00581a027.

Abstract

The self-assembly of calf brain tubulin, purified by the modified Weisenberg procedure, was examined in an adiabatic differential heat capacity microcalorimeter. Tubulin solutions at concentrations between 6 and 17 mg/mL were heated from 8 to 40 degrees C at heating rates between 0.1 and 1.0 deg/min in a pH 7.0 phosphate buffer containing 1 X 10(-3) M GTP, 1.6 X 10(-2) M MgCl2, and 3.4 M glycerol. The heat capacity change, deltaCp of the microtubule growth reaction was found to be -1600 +/- 500 cal/(deg mol) per 110 000 molecular weight tubulin dimer incorporated into microtubules, in agreement with the reported van't Hoff deltaCp value of -1500 cal/(deg mol) [Lee, J.C., & Timasheff, S.N. (1977) Biochemistry 16, 1754-1765]. The assembly reaction is characterized by a complex heat uptake pattern comprising both endothermic and exothermic processes.

摘要

采用改良的韦森堡方法纯化的小牛脑微管蛋白，在绝热量热计中进行自组装研究。浓度为6至17mg/mL的微管蛋白溶液，在含有1×10⁻³M GTP、1.6×10⁻²M MgCl₂和3.4M甘油的pH 7.0磷酸盐缓冲液中，以0.1至1.0℃/分钟的升温速率从8℃加热至40℃。发现每110000分子量的微管蛋白二聚体掺入微管时，微管生长反应的热容变化ΔCp为-1600±500 cal/(deg mol)，与报道的范特霍夫ΔCp值-1500 cal/(deg mol)一致[Lee, J.C., & Timasheff, S.N. (1977) Biochemistry 16, 1754 - 1765]。组装反应的特征是具有包括吸热和放热过程的复杂吸热情形。