巴那斯酶-巴那斯塔复合物的热稳定性

Thermostability of the barnase-barstar complex.

作者信息

Makarov A A, Protasevich I I, Lobachov V M, Kirpichnikov M P, Yakovlev G I, Gilli R M, Briand C M, Hartley R W

机构信息

Engelhardt Institute of Molecular Biology, Acad. Sci. Russia, Moscow.

出版信息

FEBS Lett. 1994 Nov 14;354(3):251-4. doi: 10.1016/0014-5793(94)01127-3.

DOI:10.1016/0014-5793(94)01127-3

PMID:7957933

Abstract

Scanning microcalorimetry was used to study heat denaturation of barnase in complex with its intracellular inhibitor barstar. The heat denaturation of the barnase-barstar complex is well approximately by two two-state transitions with the lower temperature transition corresponding to barstar denaturation and the higher temperature one to barnase denaturation. The temperature of barnase melting in its complex with barstar is 20 degrees C higher than that of the free enzyme. The barstar melting temperature is almost the same in the complex or alone (71 degrees C at pH 6.2 and 68 degrees C at pH 8.0). It seems possible that when barstar unfolds it can remain bound to barnase, while the latter unfolds only on dissociation of the denatured barstar.

摘要

采用扫描量热法研究了核糖核酸酶 barnase 与其细胞内抑制剂 barstar 形成的复合物的热变性。barnase-barstar 复合物的热变性很好地近似为两个两态转变，较低温度的转变对应于 barstar 的变性，较高温度的转变对应于 barnase 的变性。与 barstar 形成复合物的 barnase 的解链温度比游离酶高 20 摄氏度。barstar 在复合物中或单独存在时的解链温度几乎相同（在 pH 6.2 时为 71 摄氏度，在 pH 8.0 时为 68 摄氏度）。似乎有可能的是，当 barstar 展开时它可以保持与 barnase 结合，而后者仅在变性的 barstar 解离时才展开。