ISSN:
1573-6881
Keywords:
H+-ATPase
;
beef heart mitochondria
;
sulfhydryl groups
;
maleimides
;
Pi-ATP exchange
;
proton translocation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Physics
Notes:
Abstract Electron transport particles and purified H+-ATPase (F1-Fo) vesicles from beef heart mitochondria have been treated with two classes of thiol reagent, viz. membrane-impermeable organomercurials and a homologous series ofN-polymethylene carboxymaleimides (Mal-(CH2) x -COOH or AMx). The effect of such treatment on ATP-driven reactions (ATP-Pi exchange and proton translocation) has been examined and compared to the effects on rates of ATP hydrolysis. The organomercurials inhibited ATP-Pi exchange and one of them (p-chloromercuribenzoate) inhibited ATPase activity. Of the maleimide series (AMx), AM10 and AM11 inhibited both ATP-Pi exchange and ATP-driven membrane potential, but not ATPase activity. The other members of the series were essentially inactive.N-Ethylmaleimide was intermediate in its efficacy. Passive H+ conductance through the membrane sector Fo was 50% blocked by AM10, slightly blocked by AM2 andN-ethylmaleimide, and unaffected by the other members of the AMx series. The data imply that one -SH near the membrane surface and one -SH about 12 Å from the surface are functional in proton translocation through the H+-ATPase.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00743239
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