Fourier transform infrared characterization of a CuB-nitrosyl complex in cytochrome ba3 from Thermus thermophilus: relevance to NO reductase activity in heme-copper terminal oxidases.

ABSTRACT: The two heme-copper terminal oxidases of Thermus thermophilus have been shown to catalyze the two-electron reduction of nitric oxide (NO) to nitrous oxide (N2O) [Giuffre, A.; Stubauer, G.; Sarti, P.; Brunori, M.; Zumft, W. G.; Buse, G.; Soulimane, T. Proc. Natl. Acad. Sci. U.S.A. 1999, 96, 14718-14723]. While it is well-established that NO binds to the reduced heme a3 to form a low-spin heme {FeNO}7 species, the role CuB plays in the binding of the second NO remains unclear. Here we present low-temperature FTIR photolysis experiments carried out on the NO complex formed by addition of NO to fully reduced cytochrome ba3. Low-temperature UV-vis, EPR, and RR spectroscopies confirm the binding of NO to the heme a3 and the efficiency of the photolysis at 30 K. The nu(NO) modes from the light-in

SUBMITTER: Hayashi T 

PROVIDER: S-EPMC2548420 | biostudies-literature | 2007 Dec

REPOSITORIES: biostudies-literature