ISSN:
1573-6881
Keywords:
F1-ATPase
;
F0F1-ATPase
;
H+-ATPase
;
ε subunit
;
energy coupling
;
tryptophan
;
phosphorescence
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Physics
Notes:
Abstract The ATP hydrolysis rate and the ATP hydrolysis-linked proton translocation by the F0F1-ATPase of beef heart submitochondrial particles were examined in the presence of several divalent metal cations. All Me–ATP complexes tested sustained ATP hydrolysis, although to a different extent. However, only Mg- and Mn-ATP-dependent hydrolysis could sustain a high level of proton pumping activity, as determined by acridine fluorescence quenching. Moreover, the K m of the Me-ATP hydrolysis-induced proton pumping activity was very similar to the K m value of Me-ATP hydrolysis. Both oligomycin and DCCD caused the full recovery of the fluorescence, providing clear evidence for the association of Mg-ATP hydrolysis with proton translocation through the F0F1-ATPase complex. In contrast, with other Me-ATP complexes, including Ca-ATP as substrate, the proton pumping activity was undetectable, implicating an uncoupling nature for these substrates. Attempts to demonstrate the involvement of the ε subunit of the enzyme in the coupling mechanism failed, suggesting that the participation of at least the N-terminal segment of the subunit in the coupling mechanism of the mitochondrial enzyme is unlikely.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1020528432609
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