Kördel J, Drakenberg T, Forsén S, Thulin E
Department of Physical Chemistry 2, University of Lund, Sweden.
FEBS Lett. 1990 Apr 9;263(1):27-30. doi: 10.1016/0014-5793(90)80697-h.
The calcium-binding protein calbindin D9k has previously been shown to exist in two folded forms only differing in the proline cis-trans isomerism of the Gly-42-Pro-43 amide bond. This bond is located in a flexible loop connecting the two EF-hand Ca2+ sites. Calbindin D9k therefore constitutes a unique test case for investigating if the recently discovered enzyme peptidyl-prolyl cis-trans isomerase (PPIase) can affect the cis-trans exchange rate in a folded protein. The 1H NMR saturation transfer technique has been used to measure the rate of interconversion between the cis and trans forms of calbindin in the presence of PPIase (PPIase:calbindin concentration ratio 1:10) at 35 degrees C. No rate enhancement could be detected.
钙结合蛋白钙结合蛋白D9k先前已被证明仅以两种折叠形式存在，这两种形式仅在Gly-42-Pro-43酰胺键的脯氨酸顺反异构化上有所不同。该键位于连接两个EF手型Ca2+位点的柔性环中。因此，钙结合蛋白D9k构成了一个独特的测试案例，用于研究最近发现的肽基脯氨酰顺反异构酶（PPIase）是否会影响折叠蛋白中的顺反交换速率。1H NMR饱和转移技术已被用于在35摄氏度下，在PPIase（PPIase：钙结合蛋白浓度比为1：10）存在的情况下测量钙结合蛋白顺式和反式形式之间的相互转换速率。未检测到速率增强。
