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首页> 外文期刊>Biophysical Chemistry: An International Journal Devoted to the Physical Chemistry of Biological Phenomena >Effects of metabolites on the structural dynamics of rabbit muscle pyruvate kinase.
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Effects of metabolites on the structural dynamics of rabbit muscle pyruvate kinase.

机译:代谢物对兔肌肉丙酮酸激酶结构动力学的影响。

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摘要

The activity of rabbit muscle pyruvate kinase (PK) is regulated by metabolites. Besides requiring the presence of its substrates, PEP and ADP, the enzyme requires Mg(++) and K(+) for activity. PK is allosterically inhibited by Phe for activity. The presence of PEP or Phe has opposing effects on the hydrodynamic properties of the enzyme without an apparent change in secondary structure. In this study, the structural perturbation induced by ligand binding was investigated by Fourier transform infrared (FT-IR) spectroscopy. Furthermore, the structural dynamics of PK was probed by H/D exchange monitored by FT-IR. Substrates and activating metal ions induce PK to assume a more dynamic structure while Phe exerts an opposite effect. In all cases there is no significant interconversion of secondary structures. PEP is the most efficient ligand in inducing a change in the microenvironments of both helices and sheets so much so that they can be detected spectroscopically as separate bands. These results provide the first evidence for a differential effect of ligand binding on the dynamics of structural elements in PK. Furthermore, the data support the model that allosteric regulation of PK is the consequence of perturbation of the distribution of an ensemble of states in which the observed change in hydrodynamic properties represent the two extreme end states.
机译:兔肌肉丙酮酸激酶(PK)的活性受代谢产物调节。除了需要存在其底物,PEP和ADP外,该酶还需要Mg(++)和K(+)才能发挥活性。 PK被Phe变构抑制活性。 PEP或Phe的存在对酶的流体动力学特性具有相反的影响,而二级结构没有明显变化。在这项研究中,通过傅立叶变换红外(FT-IR)光谱研究了配体结合引起的结构扰动。此外,通过FT-IR监测的H / D交换来探测PK的结构动力学。底物和活化金属离子诱导PK呈现更动态的结构,而Phe发挥相反的作用。在所有情况下,二级结构之间都没有明显的相互转换。 PEP是诱导螺旋和片层微环境变化的最有效的配体,以至于可以通过光谱法将其检测为单独的条带。这些结果为配体结合对PK中结构元素动力学的不同作用提供了第一个证据。此外,数据支持该模型,即PK的变构调节是扰动状态集合分布的结果,其中观察到的流体力学性质变化表示两个极端状态。

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