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The reaction of Escherichia coli cytochrome bo with H 2 0 2 : Evidence for the formation of an oxyferryl species by two distinct routes
Author(s) -
Brittain Thomas,
Little Richard H.,
Greenwood Colin,
Watmough Nicholas J.
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(96)01253-7
Subject(s) - chemistry , cytochrome , reaction intermediate , escherichia coli , reaction mechanism , peroxide , cytochrome c , stereochemistry , crystallography , catalysis , biochemistry , enzyme , organic chemistry , mitochondrion , gene
We have re‐examined the reaction of fast oxidised cytochrome bo with H 2 O 2 in a stopped‐flow spectrophotometer. Monitoring the reaction at 582 nm allows us to observe the formation and decay of a spectroscopically distinct intermediate which accumulates transiently prior to the formation of an oxyferryl species previously characterised in this laboratory (Watmough, N.J., Cheesman, M.R., Greenwood, C. and Thomson, A.J. (1994) Biochem. J. 300, 469–475 [1]). The reaction shows three distinct phases of which the fast and intermediate phases are bimolecular and show a marked pH dependence. Initially these results appeared incompatible with the report that only one equivalent of H 2 O 2 is required to generate the oxyferryl species (Moody, A.J. and Rich, P.R. (1994) Eur. J. Biochem. 226, 731–737 [2]). However, these data can be reconciled by a branched reaction mechanism whose contributions differ according to the peroxide concentration used.