TERMINAL HEME SYNTHETIC ENZYMES

描述：（改编自研究者摘要） 血红素生物合成途径的酶，粪卟啉原氧化酶 (CPO)、原卟啉原氧化酶（PPO）和亚铁螯合酶催化 粪卟啉原转化为原卟啉， 插入亚铁以形成最终产物血红素。这些 酶具有普遍的生物化学意义，不仅因为它们独特的 催化功能，但也因为它们的矢量组织 穿过细胞膜在医学上，它们是重要的，因为减少 任何一种的活动都会导致通常称为 卟啉症本研究的目的是探讨 获得的末端三种酶的结构与功能关系 更好地理解每一个人如何发挥其催化作用 以及自然发生的各种卟啉突变如何影响 目标酶的正常功能。此外，申请人希望 以确定各种金属离子的潜在催化作用， 与这些酶中的每一种相关的辅因子（例如，铁 CPO、PPO中的黄素和亚铁螯合酶中的[2Fe.2S]簇）。的 申请人还打算扩展他们对原位膜的研究， 这三种酶的组织，并试图确定是否 另外的蛋白质参与该途径的这一部分。的 一般的方法将是利用实验 通过使用在E.杆菌 希望分子生物学方法与 生物物理方法将产生重要的新数据的催化 这些酶的功能。

DESCRIPTION: (Adapted from investigator's abstract) The terminal three enzymes of the heme biosynthetic pathway, coproporphyrinogen oxidase (CPO), protoporphyrinogen oxidase (PPO), and ferrochelatase, catalyze the conversion of coproporphyrinogen to protoporphyrin followed by insertion of ferrous iron to form the end product protoheme. These enzymes are of general biochemical interest not only for their unique catalytic functions, but also because of their vectorial organization across the membrane. Medically they are of importance because decreased activities of any one results in a disease condition known generally as porphyria. The research aims of this proposal are to investigate structure-function relationships of the terminal three enzymes to gain a better understanding of how each one carries out its catalytic role and how naturally occurring mutations of various porphyrias affect the normal functioning of the target enzyme. In addition, the applicants hope to determine the potential catalytic roles of various metal ions and cofactors that are associated with each of these enzymes (e.g., iron in CPO, flavin in PPO, and a [2Fe.2S] cluster in ferrochelatase). The applicants also intend to extend their studies on the in situ membrane organization of these three enzymes and to attempt to determine if additional proteins are involved in this portion of the pathway. The general approach will be to take advantage of the experimental versatility offered by using recombinant enzymes expressed in E. coli. It is hoped that molecular biological approaches in conjunction with biophysical approaches will yield significant new data on the catalytic functioning of each of these enzymes.