标题：Redox-linked transient deprotonation at the binuclear site in the aa3-type quinol oxidase from Acidianus ambivalens: Implications for proton translocation
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1999
卷号：96
期号：17
页码：9591-9596
DOI：10.1073/pnas.96.17.9591
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The hyperthermophilic archaeon Acidianus ambivalens expresses a membrane-bound aa3-type quinol oxidase, when grown aerobically, that we have studied by resonance Raman spectroscopy. The purified aa3 oxidase, which does not contain bound quinol, undergoes a reversible slow conformational change at heme a3 upon reduction, as indicated by a change in the frequency of its heme formyl stretching mode, from 1,660 cm-1 to 1,667 cm-1. In contrast, upon reduction of the integral membrane enzyme or the purified enzyme preincubated with decylubiquinol, this mode appears at 1,667 cm-1 much more rapidly, suggesting a role of the bound quinol in controlling the redox-linked conformational changes. The shift of the formyl mode to higher frequency is attributed to a loss of hydrogen bonding that is associated with a group having a pKa of {approx}3.8. Based on these observations, a crucial element for proton translocation involving a redox-linked conformational change near the heme a3 formyl group is postulated.
