The tonoplast-bound H(+)-translocating ATPase from Hevea latex was found to be insensitive to vanadate, diethylstilbestrol, and octylguanidine, which are specific inhibitors of the plasma membrane ATPase. The inhibitors of the mitochondrial ATPase, oligomycin and azide, and also rotenone and antimycin A, were all without effect. In contrast, trimethyltin chloride strongly inhibited the activity...

In spite of widespread concern about the possible hazards of polychlorinated biphenyls (PCBs), little is known about the action of these materials. We have therefore examined the in vitro (1, 2) and in vivo (3) effects of PCBs on the adenosine triphosphatase (ATPase) enzyme system. We have found some effects which are similar, yet distinctive, to chemically related compounds of the DDT type. A ...

We have shown [l] that the intensity of band 4 (mol. wt 3 1 000, nomenclature from [2]) of oligomycin-sensitive ATPase from beef heart mitochondria increases in the presence of thiol reagent, 2-mercaptopropionylglycine. Here we show that the intensity of this band (which is lacking in oligomycin-insensitive ATPase [3]) decreases in the presence of 0.2 MM of the uncoupler carbonylcyanide-p-trifl...

Salt tolerance in Saccharomyces cerevisiae is a complex trait, involving regulation of membrane polarization, Na(+) efflux and sequestration of Na(+) in the vacuole. Since transmembrane transport energized by H(+)-adenosine triphosphatases (ATPases) is common to all of these tolerance mechanisms, the objective of this study was to characterize the responses of the plasma membrane H(+)-ATPase, v...

The role of Ca(2+) as a cytosolic signaling molecule between porcine cardiac sarcoplasmic reticulum (SR) ATPase and mitochondrial ATP production was evaluated in vitro. The Ca(2+) sensitivity of these processes was determined individually and in a reconstituted system with SR and mitochondria in a 0.5:1 protein-to-cytochrome aa(3) ratio. The half-maximal concentration (K(1/2)) of SR ATPase was ...

In view of the unsatisfactory appearance, under the electron microscope, of liver mitochondria isolated in isotonic sucrose medium, alternative media have been examined. It was found to be advantageous to replace sucrose by raffinose, and to add levan or, preferably, dextran, together with heparin in suitable concentration. With the optimal medium, the constituents of which are raffinose, verse...

Actomyosin ATPase is the dominant ATP sink during muscle work. Its catalytic capacities in fast-twitch oxidative glycolytic fibers have long been known to exceed by about 3-fold those of slow-twitch oxidative fibers, but the relative contributions to control of metabolic rates during exercise have never been closely examined. We compared fast-twitch oxidative glycolytic and slow-twitch oxidativ...

The coupling of mitochondrial ATP synthesis and oxygen consumption (ratio of ATP and oxygen fluxes, P/O) plays a central role in cellular bioenergetics. Reduced P/O values are associated with mitochondrial pathologies that can lead to reduced capacity for ATP synthesis and tissue degeneration. Previous work found a wide range of values for P/O in normal mitochondria. To measure mitochondrial co...