DIFFRACTION STUDIES OF THE BIOTIN VITAMERS

我们建议继续研究电子和几何学 可能的反应物、中间体和产物的性质 生物素介导的羧化、脱羧和转羧， 与此同时，我们也开始研究 生物素亲和素相互作用 生物素是一种维生素， 和二氧化碳的转移;它所服务的酶参与了关键的 代谢过程，如脂肪生成、脂肪酸合成和 丙酸精加工 生物素酶共有许多结构上的差异。 和机械特征;我们的结果将密切相关， 理解他们所有人。 抗生物素蛋白是一种存在于大多数动物白色组织中的蛋白质 鸡蛋;它结合生物素的韧性无与伦比的非共价键 交互. 生物素-抗生物素蛋白相互作用正在成为一个极端的 在分离和纯化科学以及在 细胞化学和免疫定位程序。 从一个机械的 从生物素-抗生物素蛋白相互作用的观点来看，人们对其了解甚少。 在生物素作为辅酶和生物化学工具的研究中，我们将 通过实验性高分辨率X射线技术 衍射和理论从头算量子力学，性质， 与这些功能密切相关的模型系统。 这两种技术都产生详细的 分子的几何和电子性质的信息。 通过 观察生物素介导过程中的个体参与者， 在相互作用之前监视关键中间体的状态。 通过寻找 在成对的参与者中，通过共结晶， 静电相互作用的实验确定的属性， 所涉及的个体，或通过计算集合属性 从理论上讲，我们可以监视这些动态过程， 生物素的功能 这些研究的核心是一个更清晰的 了解机制，特别是电子和 几何细节，生物素的作用。

We propose to continue our investigations of the electronic and geometric properties of the likely reactants, intermediates, and products of biotinmediated carboxylations, decarboxylations, and transcarboxylations, and at the same time inaugurate our studies of model participants in the biotinavidin interaction. Biotin is a vitamin responsible for the uptake and transfer of carbon dioxide; the enzymes it serves are involved in key metabolic processes such as gluconeogenesis, fatty acid synthesis and propionate elaboration. The biotin enzymes share a number of architectural and mechanistic characeristis; our results will be germane in the understanding of them all. Avidin is a protein found in the whites of most poultry eggs; it binds biotin with a tenacity unparalleled in non-covalent interactions. The biotin-avidin interaction is becoming an extremely important tool in both separation and purification science and in cytochemical and immunological localization procedures. From a mechanistic point of view the biotin-avidin interaction is only poorly understood. In our studies of biotin as coezyme and as a biochemical tool we will investigate, by the techniques of experimental high resolution x-ray diffraction and theoretical ab initio quantum mechanics, the properties of model systems germane to these functions. Both techniques yield detailed information about the geometric and electronic properties of molecules. by looking at individual participants in biotin-mediated processes we can surmise the states of key intermediates prior to interaction. By looking at pairs of participants, either by cocrystallization, by modeling electrostatic interaction from the experimentally determined properties of the individuals involved, or by computation of ensemble properties theoretically, we can surmise the dynamic processes involved in these functions of biotin. At the heart of these studies is a clearer understanding of the mechanisms, and in particular the electronic and geometric details, by which biotin acts.