Premium
A rapid burst preceding the steady‐state rate of H + ‐transhydrogenase during illumination of chromatophores of Rhodobacter capsulatus
Author(s) -
Palmer Tracy,
Jackson J.Baz
Publication year - 1990
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 - 10.1016/0014-5793(90)80806-t
Subject(s) - rhodobacter , steady state (chemistry) , chromatophore , chemistry , rhodospirillales , rhodospirillaceae , biophysics , photosynthesis , biochemistry , biology , mutant , genetics , gene , organic chemistry
At the onset of illumination of chromatophores there was a burst ( t approx. 5 ms) in the rate of the H + ‐transhydrogenase reaction before establishment of the steady‐state rate. The burst was suppressed at high pH with a p K a , of approx. 8.5. The burst and the steady‐state rate were inhibited by either (i) a combination of myxothiazol and carbonylcyanide‐ p ‐trifluoromethoxyphenylhydrazone, or (ii) NAD + or (iii) dicyclohexylcarbodiimide. The results support a model in which substrate binding to H + ‐transhydrogenase is relatively fast. A subsequent slow step is accelerated by the protonmotive force and a third step, possibly product release, is rate‐limiting in steady‐state turnover during illumination.