棘阿米巴肌球蛋白II和骨骼肌肌球蛋白的热变性

Thermal unfolding of Acanthamoeba myosin II and skeletal muscle myosin.

作者信息

Zolkiewski M, Redowicz M J, Korn E D, Ginsburg A

机构信息

Laboratory of Biochemistry, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.

出版信息

Biophys Chem. 1996 Apr 16;59(3):365-71. doi: 10.1016/0301-4622(95)00129-8.

DOI:10.1016/0301-4622(95)00129-8

PMID:8672724

Abstract

Studies on the thermal unfolding of monomeric Acanthamoeba myosin II and other myosins, in particular skeletal muscle myosin, using differential scanning calorimetry (DSC) are reviewed. The unfolding transitions for intact myosin or its head fragment are irreversible, whereas those of the rod part and its fragments are completely reversible. Acanthamoeba myosin II unfolds with a high degree of cooperativity from ca. 40-45 degrees C at pH 7.5 in 0.6 M KCl, producing a single, sharp endotherm in DSC. In contrast, thermal transitions of rabbit skeletal muscle myosin occur over a broader temperature range (ca. 40-60 degrees C) under the same conditions. The DSC studies on the unfolding of the myosin rod and its fragments allow identification of cooperative domains, each of which unfolds according to a two-state mechanism. Also, DSC data show the effect of the nucleotide-induced conformational changes in the myosin head on the protein stability.

摘要

本文综述了利用差示扫描量热法（DSC）对单体棘阿米巴肌球蛋白II和其他肌球蛋白，特别是骨骼肌肌球蛋白进行热解折叠的研究。完整肌球蛋白或其头部片段的解折叠转变是不可逆的，而杆状部分及其片段的解折叠转变则是完全可逆的。在0.6 M KCl、pH 7.5条件下，棘阿米巴肌球蛋白II在约40 - 45℃时高度协同解折叠，在DSC中产生单一、尖锐的吸热峰。相比之下，在相同条件下，兔骨骼肌肌球蛋白的热转变发生在更宽的温度范围（约40 - 60℃）。对肌球蛋白杆状部分及其片段解折叠的DSC研究能够识别协同结构域，每个结构域都按照两态机制解折叠。此外，DSC数据显示了核苷酸诱导的肌球蛋白头部构象变化对蛋白质稳定性的影响。