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首页> 外文期刊>Biophysical Chemistry: An International Journal Devoted to the Physical Chemistry of Biological Phenomena >High pressure response of H-1 NMR chemical shifts of purine nucleotides
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High pressure response of H-1 NMR chemical shifts of purine nucleotides

机译：嘌呤核苷酸H-1 NMR化学位移的高压响应

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摘要

The study of the pressure response by NMR spectroscopy provides information on the thermodynamics of conformational equilibria in proteins and nucleic acids. For obtaining a database for expected pressure effects on free nucleotides and nucleotides bound in macromolecular complexes, the pressure response of H-1 chemical shifts and J-coupling constants of the purine 5'-ribonucleotides AMP, ADP, ATP, GMP, GDP, and GTP were studied in the absence and presence of Mg2+-ions. Experiments are supported by quantum-chemical calculations of populations and chemical shift differences in order to corroborate structural interpretations and to estimate missing data for AMP. The preference of the ribose S puckering obtained from the analysis of the experimental J-couplings is also confirmed by the calculations. In addition, the pressure response of the non-hydrolysable GTP analogues GppNHp, GppCH(2)p, and GTP gamma S was examined within a pressure range up to 200 MPa. As observed earlier for P-31 NMR chemical shifts of these nucleotides the pressure dependence of chemical shifts is clearly non-linear in most cases. In di- and tri-phospho nucleosides, the resonances of the two protons bound to the ribose 5' carbon are non-equivalent and can be observed separately. The gg-rotamer at C4'-C5' bond is strongly preferred and the downfield shifted resonance can be assigned to the H5 '' proton in the nucleotides. In contrast, in adenosine itself the frequencies of the two resonances are interchanged.
机译：NMR光谱对压力响应的研究提供了关于蛋白质和核酸的构象均衡的热力学的信息。用于获得对大分子复合物中结合的自由核苷酸和核苷酸的预期压力效应的数据库，嘌呤5'-核糖核苷酸AMP，ADP，ATP，GMP，GDP和J-偶联常数的H-1化学换向和J偶联常数的压力响应。在缺乏和存在的Mg 2 +离子的情况下研究了GTP。通过量子化学计算的群体和化学变化差异的支持支持实验，以证实结构解释和估算AMP的缺失数据。从实验J联轴器分析中获得的核糖S褶皱的偏好也通过计算来证实。另外，在高达200MPa的压力范围内检查非水解GTP类似物GPPNHP，GPPCH（2）P和GTPγs的压力响应。如前所述，对于这些核苷酸的P-31 NMR化学变化，化学位移的压力依赖性在大多数情况下是显而易见的。在二磷核苷中，与核糖5'碳结合的两个质子的共振是非等同的，并且可以单独观察。 C4'-C5'键处的GG转子是强烈优选的，并且可以将下场移位的共振分配给核苷酸中的H5'质子。相反，在腺苷本身中，两个共振的频率互换。

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