Spectroscopic and Computational Investigation of Cytrochrome C Oxidase and Models

描述（由申请方提供）：细胞色素c氧化酶（CcO）是关键的末端呼吸酶，负责利用需氧生物体能量产生所需的双氧氧化能力。在化学上，反应的净产物是两当量的水，其通过伴随着H+穿过线粒体膜以产生化学渗透势的泵送的分子氧的彻底还原而产生。由于CcO的基本生化功能，与功能失调突变相关的病理学通常被证明与生命不相容。例如，以张力减退和心脑肌病为特征的严重婴儿疾病与减弱的CcO功能有关。同样，由老年人群中的衰老过程引起的CcO突变有助于减少肌肉质量以及其他退行性过程，使CcO的研究成为一个吸引人的目标。CcO中的分子氧还原活性位点在金属蛋白中是独特的，这吸引了合成和生物化学家的关注，其共同目标是理解最终导致内在反应性的结构-功能关系。尽管几十年的紧张的研究工作，动力学捕获的酶的中间体的直接光谱探测还没有提供的信息，在一个详细的水平所需的O-O键断裂的机制的表征。因此，这些信息必须来自小分子模型研究和理论，以及大量的酶数据。模型复合物将被用来测试的可行性，过氧中间体在CCO催化的理论预测。结合对CcO态PM的直接光谱探测，本研究将进一步验证活性位的可能性 酪氨酸作为氢原子供体起作用。最后，自旋状态，自旋耦合，和铜离子denticity的影响将摆脱重要的洞察方向的氧裂解坐标，并提供一个功能为基础的理论基础的活性位点的结构元素。这些研究需要应用先进的光谱学，如共振拉曼，X-射线和光学磁圆二色性，电子顺磁共振，X-射线吸收结合电子结构方法，如DFT的结果与酶催化。因此，这项研究需要对受训人员进行丰富的培训。 公共卫生相关性：这些研究将产生分子水平上的细节有关的CcO，洞察有用的理解CcO突变的发病机制，并可能作为“绿色”化学催化剂的基础。

DESCRIPTION (provided by applicant): Cytochrome c oxidase (CcO) is the key, terminal respiratory enzyme responsible for harnessing the oxidative power of dioxygen necessary for energy production in aerobic organisms. Chemically, the net product of the reaction is two equivalents of water, generated by exhaustive reduction of dioxygen concomitantly with pumping of H+ across the mitochondrial membrane to generate a chemiosmotic potential. Due to CcO's essential biochemical function, the pathology associated with dysfunctional mutation generally proves incompatible with life. For example, severe infantile diseases characterized by hypotonia and cardioencephalomyopathy have been linked to attenuated CcO function. Similarly, mutations in CcO caused by the aging process in older populations contribute to reduced muscle mass among other degenerative processes, making study of CcO an engaging target. The active site of dioxygen reduction in CcO is unique among metalloproteins, which attracts the attention of synthetic and biochemists alike with the common goal of understanding the structure-function relationships that ultimately lead to the intrinsic reactivity. Despite decades of intense research effort, direct spectroscopic probing of kinetically trapped enzymatic intermediates has not provided information in a level of detail necessary for characterization of the mechanism of O-O bond rupture. Therefore, the information must come from small molecule model studies and theory in conjunction with the large body of enzymatic data. Model complexes will be used to test the feasibility of a peroxo intermediate during CcO catalysis as predicted by theory. Combined with direct spectroscopic probing of CcO state PM, this study will further test the possibility of an active site tyrosine functioning as a hydrogen atom donor. Finally, the effect of spin state, spin coupling, and copper ion denticity will shed important insight into the direction of the oxygen cleavage coordinate and provide a function based rationale for active site structural elements. The studies require application of advanced spectroscopies such as resonance Raman, X-ray and optical magnetic circular dichroism, electron paramagnetic resonance, and X-ray absorption to be combined with electronic structure methods such as DFT to relate the results to enzymatic catalysis. Thus, the study entails a rich training component for the Trainee. PUBLIC HEALTH RELEVANCE: These studies will yield molecular level details concerning dioxygen reduction by CcO, insight useful for understanding pathogenesis of CcO mutation and perhaps as a basis for "green" chemical catalysts.