EXAFS STUDIES OF NON-HEME IRON ENZYME INTERMEDIATES AND MODEL COMPOUNDS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The diiron centers in non-heme enzymes activate dioxygen to carry out many different important metabolic transformations. In the reactions of these enzymes with O2 various intermediates have been observed which are critical for understanding the reaction mechanisms. XAS has played a key role in establishing the core structures of some of these intermediates. We propose to use EXAFS to study the short-lived intermediates of several non-heme diiron enzymes and compare their structures with those of the three intermediates already reported. Specifically, we will study the peroxo intermediate of the ferritin from E. coli, intermediate Q of methane monooxygenase (MMO) in the presence of substrate, and metastable (but as yet not crystallized) model complexes related to the oxygen activation chemistry of these nonheme diiron enzymes.