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Research has been conducted on the heme-copper cbb (sub)3 cytochrome oxidase. The structural characteristics of the cbb (sub)3 binuclear center have been investigated and the results are reported.

Studies oxygen gas migration in the putative oxygen gas channel of cytochrome ba[sub3] and its effects to the properties of the binuclear heme from Thermus thermophilous. Use of the Fourier transform infrared spectra; Absence of any changes on the frequencies of the C-O stretching modes of heme; Indication of the rate of decay of the transient Cu[subb][sup1+]-CO complex.

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.

We report the first evidence for the existence of the equilibrium Cu(B)1+-CO species of CO-bound reduced cytochrome ba(3) from Thermus thermophilus at room temperature. The frequency of the C-O stretching mode of Cu(B)1+-CO is located at 2053 cm(-1) and remains unchanged in H(2)O/D(2)O exchanges and, between pD 5.5 and 9.7, indicating that the chemical environment does not alter the protonation state of the Cu(B) histidine ligands. The data and conclusions reported here are in contrast to the changes in protonation state of Cu(B)-His-290, reported recently (Das, T. K., Tomson, F. K., Gennis, R. B., Gordon, M., and Rousseau, D. L. (2001) Biophys. J. 80, 2039-2045 and Das, T. P., Gomes, C. M., Teixeira, M., and Rousseau, D. L. (1999) Proc. Natl. Acad. Sci. U. S. A. 96, 9591-9596). The time-resolved step-scan FTIR difference spectra indicate that the rate of decay of the transient Cu(B)1+-CO complex is 34.5 s(-1) and rebinding to heme a(3) occurs with k(2) = 28.6 s(-1). The rate of decay of the transient Cu(B)1+-CO complex displays a similar time constant as the absorption changes at 1694(+)/1706(-), attributed to perturbation of the heme a(3) propionates (COOH). The nu(C-O) of the transient Cu(B)1+-CO species is the same as that of the equilibrium Cu(B)1+-CO species and remains unchanged in the pD range 5.5-9.7 indicating that no structural change takes place at Cu(B) between these states. The implications of these results with respect to proton pathways in heme-copper oxidases are discussed.