TY  - JOUR
A1  - Pinakoulaki, Eftychia
A1  - Pfitzner, Ute
A1  - Ludwig, Bernd
A1  - Varotsis, Constantinos
T1  - The role of the cross-link His-Tyr in the functional properties of the binuclear center in cytochrome c oxidase
T2  - Journal of biological chemistry
N2  - Resonance Raman and Fourier transform infrared spectroscopies have been used to study the aa(3)-type cytochrome c oxidase and the Y280H mutant from Paracoccus denitrificans. The stability of the binuclear center in the absence of the Tyr(280)-His(276) cross-link is not compromised since heme a(3) retains the same proximal environment, spin, and coordination state as in the wild type enzyme in both the oxidized and reduced states. We observe two C-O modes in the Y280H mutant at 1966 and 1975 cm(-1). The 1975 cm(-1) mode is assigned to a gamma-form and represents a structure of the active site in which Cu(B) exerts a steric effect on the heme a(3)-bound CO. Therefore, the role of the cross-link is to fix Cu(B) in a certain configuration and distance from heme a(3), and not to allow histidine ligands to coordinate to Cu(B) rather than to heme a(3), rendering the enzyme inactive, as proposed recently (Das, T. K., Pecoraro, C., Tomson, F. L., Gennis, R. B., and Rousseau, D. L. (1998) Biochemistry 37, 14471-14476). The results provide solid evidence that in the Y280H mutant the catalytic site retains its active configuration that allows O(2) binding to heme a(3). Oxygenated intermediates are formed by mixing oxygen with the CO-bound mixed-valence wild type and Y280H enzymes with similar Soret maxima at 438 nm.
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/76037
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-760374
SN  - 0021-9258
VL  - 277.2002
IS  - 16
SP  - 13563
EP  - 13568
PB  - American Society for Biochemistry and Molecular Biology Publications
CY  - Bethesda, Md
ER  -