O2 ACTIVATION BY MOSSBAUER SPECTROSCOPY

本研究旨在阐明多种含铁酶在氧活化和醋酸合成过程中的结构和功能。此外，还建议研究模拟所研究酶的结构和电子特征的合成配合物的电子结构。采用了57Fe穆斯堡尔谱、电子顺磁共振和SQUID磁强计等实验技术。(1)继续对二铁蛋白甲烷单加氧酶、核糖核苷酸还原酶、delta9去饱和酶、甲苯单加氧酶、苯酚羟化酶和烷烃羟化酶进行研究，重点研究催化中间体的电子结构特征。(2)本研究将辅以模型配合物的研究，以深入了解酶活性位点的电子结构。(3) FNR转录因子的分离和全株研究将继续进行。(4)将牛油果中1-氨基丙烷-1-羧酸氧化酶克隆到大肠杆菌中进行穆斯堡尔研究。卡耐基梅隆大学的柯林斯实验室设计了多种含铁络合物，它们是染料和纸浆漂白的有力催化剂，在绿色化学方面很有希望。这些配合物的高价态将被研究，目的是表征它们的催化行为。这些复合物也可以作为蛋白质FeIV状态的光谱基准。(6)继续对热醋酸梭菌和红螺旋菌一氧化碳脱氢酶的镍- [4Fe-4S]簇结构进行实验和理论研究。这些研究将扩展到铁氢化酶，它似乎也有一个涉及[4Fe4S]簇的簇组装。

This proposal seeks to elucidate the structure and function of a variety of iron-containing enzymes involved in oxygen activation and acetate synthesis. Moreover, it is proposed to investigate the electronic structure of synthetic complexes that mimic structural and electronic features of the enzymes under study. The experimental techniques employed are 57Fe Mossbauer spectroscopy, Electron Paramagnetic Resonance and SQUID magnetometry. (1) Studies of the diiron proteins methane monooxygenase, ribonucleotide reductase, delta9 desaturase, toluene monooxygenase, phenol hydroxylase and alkane hydroxylase will be continued with particular focus on characterizing the electronic structure of catalytic intermediates. (2) This research will be complemented by studies of model complexes to gain insight into the electronic structure of the active sites of the enzymes. (3) Studies of FNR transcription factor as isolated and in whole E.coli cells will be continued. (4) Mossbauer studies of 1-aminopropane-1-carboxylate oxidase from avocado, cloned into E. coli, will be performed. (5) The Collins laboratory at Carnegie Mellon University has designed a variety of iron-containing complexes that are potent catalysts for dye and pulp bleaching, and that have high promise in green chemistry. The high- valent states of these complexes will be investigated with the goal of characterizing their catalytic behavior. These complexes are also of interest as spectroscopic benchmarks for FeIV states in proteins. (6) Experimental and theoretical studies of the structure the Nickel- [4Fe-4S] cluster assemblies of carbon monoxide dehydrogenases isolated from Clostridium thermoaceticum and Rhodospirillum rubrum will be continued. These studies will be extended to iron-hydrogenases which appear to have a cluster assembly involving a[4Fe4S] cluster as well.