ISSN:
1432-072X
Keywords:
Rhodobacter capsulatus
;
Nitrate reduction
;
Auxiliary electron transport
;
Myxothiazol
;
2-n-heptyl-4-hydroxyquinoline-N-oxide
;
Ubiquinone pool
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The effects of various electron transport inhibitors upon the rates of reduction NO 3 - , dimethyl sulphoxide (DMSO) and N2O in anaerobic suspensions of Rhodobacter capsulatus have been studied. A new method for the determination of the rates of reduction of these auxiliary oxidants in intact cells is presented, based on the proportionality observed between the concentration of oxidant and the duration of the electrochromic carotenoid bandshift. For NO 3 - and N2O good agreement was found between rates of reduction determined using electrodes and those determined by the electrochromic method. Myxothiazol and antimycin A had no effect on the rates of reduction of NO 3 - and DMSO suggesting that the cytochrome b/c 1complex is not involved in electron transport to these oxidants. 2-n-heptyl-4-hydroxyquinoline-N-oxide (HOQNO) inhibited at two sites, one within the cytochrome b/c 1complex and the other on the nitrate reducing pathay, but had no effect on electron transport to N2O or DMSO. In both intact cells and cell free extracts, HOQNO had no effect on the nitrate dependent re-oxidation of reduced methylviologen (MVH2), a direct electron donor to nitrate reductase. Our data are consistent with a branch point for the auxiliary electron transport pathways at the level of the ubiquinone pool.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00402344
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