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Resonance Raman spectroscopy (RR) a technique that enables iron ligand stretching modes to be identified to characterize the NO-bound complex of cytochrome cbb(sub 3) oxidase is described. The existence of a five-coordinate heme b(sub 3) Fe(super 2+)-NO complex was found.

Examines the influence of the heme Fe-CO complex of cytochrome cbb[sub 3]-CO at ambient temperature formation on the decay of the transient Cu[sub B]-CO complex. Use of time-resolved fourier transform infrared spectroscopy; Catalyzation of molecular oxygen reduction by the complex; Importance of photodynamics of cbb[sub 3]-CO for elucidating the mechanisms for legal entry/exit in heme-cooper oxidase.

Understanding the chemical nature of the nitric oxide (NO) moiety of nitrosylheme copper oxidases is crucial for elucidation of the NO activation process. In the present work, direct resonance Raman spectroscopic observation of both the Fe(2+)-NO and the N-O stretching modes unambiguously establishes the vibrational characteristics of the NO-bound heme moiety in cytochrome cbb(3) from Pseudomonas stutzeri. Addition of NO to fully reduced enzyme causes the rupture of the proximal His-heme b(3) bond resulting in the formation of a five-coordinate heme b(3)(2+)-NO species with nu(Fe-NO) and nu(NO) at 524 and 1679 cm(-1), respectively. The frequencies of the nitrosyl species we detect are very similar to those obtained in other model- and protein heme-NO complexes. To account for this observation, we propose a model describing the oxidation and ligand-binding states in fully reduced cytochrome cbb(3) upon addition of NO.