ISSN:
1573-6881
Keywords:
TF1-ATPase
;
α3β3 complex
;
α3β3γ complex
;
rhodamine 6G
;
lauryldimethylamine oxide
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Physics
Notes:
Abstract The ATPase activity of the F1-ATPase from the thermophilic bacterium PS3 is stimulated at concentrations of rhodamine 6G up to about 10 µM where 70% stimulation is observed at 36°C. Half maximal stimulation is observed at about 3 µM dye. At rhodamine 6G concentrations greater than 10 µM, ATPase activity declines with 50% inhibition observed at about 75 µM dye. The ATPase activities of the α3β3γ and α3β3γδ complexes assembled from isolated subunits of TF1 expressed inE. coli deleted of theunc operon respond to increasing concentrations of rhodamine 6G nearly identically to the response of TF1. In contrast, the ATPase activities of the α3β3 and α3β3δ complexes are only inhibited by rhodamine 6G with 50% inhibition observed, respectively, at 35 and 75 µM dye at 36°C. The ATPase activity of TF1 is stimulated up to 4-fold by the neutral detergent, LDAO. In the presence of stimulating concentrations of LDAO, the ATPase activity of TF1 is no longer stimulated by rhodamine 6G, but rather, it is inhibited with 50% inhibition observed at about 30 µM dye at 30°C. One interpretation of these results is that binding of rhodamine 6G to a high-affinity site on TF1 stimulates ATPase activity and unmasks a low-affinity, inhibitory site for the dye which is also exposed by LDAO.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00770254
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