9507061 Hoffman Multifrequency advanced paramagnetic resonance (amr) spectroscopy will be used to characterize the catalytic centers of multi- metallic enzymes as part of a multidisciplinary effort that involves biochemists, molecular biologists, and microbiologists. This research, which will utilize a unique capacity to employ CW and pulsed electron-nuclear double resonance (endor)and electrol spin-echo envelope modulation (eseem) techniques at both X and Q Bands, involves a number of protein systems, emphasizing three areas: (I) Binuclear non-heme iron centers and amr of non-Kramers (NK) doublets of integer-spin systems (nk-amr); (II) The nitrogenase MoFe protein; (III) Enzymes from hyperthermophiles. %%% AMR methods provide detailed analytical, structural, and electronic information about the catalytic sites of metalloenzymes, and thus play a vital role in characterizing their mechanisms of function. It is of course necessary to obtain this information because metalloenzymes play key roles in biological processes. However, this effort is acquiring increasing significance because of the growing importance of such enzymes in industry and biotechnology (eg., nitrile hydratase, a nonheme Fe enzyme is used to convert acrylonitrile to acrylamide), in agriculture (nitrogenase is the enzyme that fixes nitrogen in nature), and in efforts at bioremediation of toxic wastes (eg., oxygenases). ***