Spectroscopic studies of molybdenum enzymes

钼是唯一在动物体内具有已知功能的第二排过渡元素。它在几乎所有生物的酶中发挥功能，从细菌到植物，再到无脊椎动物和哺乳动物。所有的钼酶都含有被一种不寻常的含硫辅因子结合的金属。尽管这些酶具有共同的结构元素，但在所催化的不同化学反应中都是引人注目的，尽管几乎所有的反应都是两电子氧化还原反应，其中一个氧原子转移到钼或从钼转移出来。钼酶的功能也是多种多样的；例如，它们在微生物呼吸、绿色植物的氮素吸收、控制昆虫眼睛颜色和人类健康方面发挥着重要作用。这项拟议的工作是利用基于同步加速器的X射线吸收光谱技术对钼酶的所有主要家族进行的系统研究。我们建议使用一种新的整体方法来结合来自X射线吸收光谱、先进的计算机分子模拟和可用的蛋白质晶体结构的信息来获得迄今为止最准确的活性部位的图像。这项工作的最终目标是对酶使用的催化机制进行深入的量化、结构和电子理解，比较不同家族之间和内部的差异。这将有助于更好地理解钼酶是如何实现其非凡的功能多样性的。这项研究的好处有三个方面。I)结果将为一组重要的酶产生详细的见解。二)所制定的整体方法将广泛适用于所有金属蛋白研究。3)这项研究将加强加拿大在利用结构分子生物学的主要同步加速器工具之一--X射线吸收光谱学方面的努力。

Molybdenum is the only second-row transition element with a known function in animals. It fulfills functional roles in enzymes in almost all living creatures, from bacteria through plants to invertebrates and mammals. The molybdenum enzymes all contain the metal bound by an unusual sulfur-containing cofactor. Despite possessing common structural elements, the enzymes are remarkable in the range of different chemical reactions that are catalyzed, although almost all are two-electron oxidation-reduction reactions in which an oxygen atom is transferred to or from the molybdenum. The functional roles filled by molybdenum enzymes are equally diverse; for example, they play essential roles in microbial respiration, in the uptake of nitrogen in green plants, in controlling insect eye color, and in human health. The proposed work is a systematic study of all the major families of molybdenum enzymes using the synchrotron-based technique of X-ray absorption spectroscopy. We propose to use a novel holistic approach in combining information from X-ray absorption spectroscopy, advanced computer molecular modeling, and available protein crystal structures to obtain the most accurate picture yet of the active sites. The ultimate goal of the work is to develop an in-depth quantitative structural and electronic understanding of the catalytic mechanisms used by the enzymes, comparing and contrasting between and within the different families. This will lead to an improved understanding of how molybdenum enzymes achieve their remarkable functional diversity. The benefits of this research are three-fold. i) The results will yield detailed insights for an important group of enzymes. ii) The holistic approach developed will be broadly applicable to all metalloprotein studies. iii) The research will strengthen the Canadian effort in utilizing one of the major synchrotron tools in structural molecular biology - X-ray absorption spectroscopy.