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：1
页码：35-37
DOI：10.1073/pnas.96.1.35
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Pathways of proton entry have been identified in the proton-translocating heme-copper oxidases, but the proton exit pathway is unknown. Here we report experiments with cytochrome bo3 in Escherichia coli cells that may identify the beginning of the exit pathway. Systematic mutations of arginines 438 and 439 (R481 and R482 in the E. coli enzyme), numbering as in cytochrome aa3 from bovine heart mitochondria, which interact with the ring D propionates of the two heme groups, reveal that the D propionate of the oxygen-binding heme is involved in proton pumping; its anionic form must be stabilized in order for proton translocation to occur. This may locate the beginning of the pathway by which pumped protons exit from the enzyme structure.
