ISSN:
1432-072X
Keywords:
Key words Quinol oxidase
;
Bacillus subtilis
;
Electron
;
transport
;
Respiration
;
Menaquinone
;
qox Deletion
;
mutants
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Menaquinol oxidase isolated from the membrane of Bacillus subtilis W23 was found to consist of four polypeptides (QoxA, B, C, and D) that were predicted by the sequence of the qox operon of B. subtilis 168 (Santana et al. 1992). The preparation contained 7 mol cytochrome aa 3 per g protein, which corresponds to 2 mol heme A per mol enzyme of 144 kDa molecular mass. Respiration with dimethylnaphthoquinol catalyzed by the enzyme was ten times faster than that with menadiol. Activities with more electropositive quinols were negligible. The activity of the enzyme was inhibited by equimolar amounts of HQNO, while antimycin, myxothiazol, and stigmatellin were more than tenfold less effective. When cells of both strains of B. subtilis (W23 and 168) were grown with glucose, quinol respiration was an order of magnitude more active than respiration with N,N,N',N'-tetramethyl-1,4-phenylenediamine plus ascorbate. Surprisingly, the same result was obtained with mutant strains lacking qoxB. As cytochromes a and d were virtually absent, a second quinol oxidase, possibly of the cytochrome o-type, was apparently formed by the mutants.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00272132
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