Administration of reseaches on principles of protein architecture

蛋白质是具有重要生物学功能的分子，其三维结构决定了蛋白质的构象波动模式。随着温度的降低，波动被抑制，并在约200 K时显示出类似玻璃化转变的现象。低于200 K，蛋白质功能通常会丧失。这些观察结果表明，在玻璃化转变温度以上获得的波动对生物功能至关重要。原则上，玻璃化转变现象可以通过低温X射线晶体学研究以及各种光谱技术检测到原子细节。这项工作是由京都大学的Go和Kidera以及慕尼黑工业大学的Parak两个小组合作完成的。慕尼黑小组在不同的低温下对肌红蛋白晶体进行了低温X射线测量。京都研究小组对Parak提供的衍射数据进行了分析，使用了一种称为NOR的精细化方法。 ...更多信息 模态细化我们进行了密切的沟通，包括从京都到慕尼黑和从慕尼黑到京都的两次访问。去年12月，Parak访问日本时，在第五届“蛋白质结构原理”研讨会上发表了关于这一主题的演讲。由肌红蛋白晶体X射线衍射的简正模精修得到的内涨落<R ^<**>2>int与温度的关系为<R^<**>2>int = AT + B，其中T为绝对温度，A和B为常数。A值与简正波分析预测值吻合较好。这意味着低于玻璃化转变温度的构象亚态与高于转变温度的构象亚态相同。这就是为什么我们没有观察到<R^<**>2>int在玻璃化转变温度下突然增加的原因。因此，值B表示静态无序。这是X射线衍射检测相干散射的观点，它与其它检测非相干散射的光谱技术如穆斯堡尔吸收光谱完全不同。少

Proteins, the molecule which play crucially important biological functions, possess its own pattern of conformational fluctuations depending on the three dimensional structure. The fluctuations are suppressed with decreasing temperature, and show a glass transition-like phenomenon at about 200 K.Below 200 K, the protein function is usually lost. Such observations indicate that the fluctuations acquired above the glass transition temperature is crucial for the biological functions. In principle, the glass transition phenomenon can be detected to the atomic detail by a cryo X-ray crystallographic study, as well as various spectroscopic techniques.This work was done by the cooperation between two groups, Go and Kidera in Kyoto University and Parak in Technical University Muenchen. Muenchen group did cryo X-ray measurements at various cryo-temperatures for myoglobin crystals. Kyoto group did analyses of diffraction data provided by Parak using an elaborated refinement method called the nor … More mal mode refinement. We have had close communication including each of two times visits from Kyoto to Muenchen and from Muenchen to Kyoto. Last December when Parak visited Japan, he presented a lecture on this topics in the 5-th workshop of "Principles of protein architectures".The results of the cooperative work is summarized as follows. The internal fluctuations,<R^<**>2>int, derived from the normal mode refinement of X-ray diffraction from myoglobin crystals was found to have temperature dependence of<R^<**>2>int = AT + Bwhere T is absolute temperature, and A an B are constants. The value of A has a good agreement with the value predicted by a normal mode analysis. This means that the conformational substates available below the glass transition temperature is the same as those above the transition temperature. This is why we do not observe abrupt increase in <R^<**>2>int at the glass transition temperature. Therefore, the value B represents the static disorder. This is the view of X-ray diffraction detecting the coherent scattering, which is totally different from the other spectroscopic techniques detecting the incoherent scattering, likeMossbauer absorption spectroscopy. Less