1. The ATPase activity of insect mitochondria has been investigated. A comparison was made to determine the distribution and nature of such activity in other isolated fractions of the house fly, Musca domestica L. 2. The ATPase in insect mitochondria is specific in that orthophosphate can be cleaved only from ATP. The Michaelis-Menten constant K(8) = 2.78 x 10(-3)M and V(max.) = 76 micrograms P...

Tupling, R., H. Green, G. Senisterra, J. Lepock, and N. McKee. Ischemia-induced structural change in SR Ca21ATPase is associated with reduced enzyme activity in rat muscle. Am J Physiol Regulatory Integrative Comp Physiol 281: R1681–R1688, 2001.—In this study, we employed an in vivo model of prolonged ischemia in rat skeletal muscle to investigate the hypothesis that structural modifications to...

introduction: the regulation of the body fluid content (osmoregulation) of an aquatic animal, is performed by several organs. in fish, osmoregulatory mechanisms are based on the function of specialized cells (ionocytes) located in various tissues and organs including gills. na+, k+-atpase is one of the main osmoregulatory enzymes enabling the use of atp as a source of energy for ion transport t...

The ATPase 6 accessory protein 2 (ATP6AP2)/(pro)renin receptor (PRR) is essential for the biogenesis of active vacuolar H(+)-ATPase (V-ATPase). Genetic deletion of ATP6AP2/PRR causes V-ATPase dysfunction and compromises vesicular acidification. Here, we characterized the domains of ATP6AP2/PRR involved in active V-ATPase biogenesis. Three forms of ATP6AP2/PRR were found intracellularly: full-le...

Triton X-100 (TX-100) extraction of Spiruplasnta citvi plasma membrane solubilized two types of ATPase differing in their pH of maximum activity. The activity measured at pH 8.5 was inhibited by vanadate and the activity measured at pH 6-5 was not. The vanadate-sensitive ATPase had a relatively basic isoelectric point (8.65) and therefore could be separated from the vanadate-insensitive ATPase ...

1. An oligomycin -sensitive ATPase was isolated and partially purified from beef heart mitochondria. The specific activity of ATPase sensitive to oligomycin of the fraction was five to eight times that of aged mitochondrial or of DNP-induced mitochondrial ATPase assayed under the same condition. 2. Electron micrographs of the partially purified oligomycinsensitive ATPase reveal a structure in w...

influence of folic acid on the cns is still unclear. folate has a neuroprotective effect, while on the other hand excess folate can exacerbate seizures in epileptics. the aim of the present study was to examine the effect of subchronic administration of folic acid on behavioural and electroencephalographic (eeg) characteristics of dl homocysteine thiolactone induced seizures in adult rats. t...

1. The Na(+)-plus-K(+)-stimulated adenosine triphosphatase [(Na(+),K(+))-ATPase] of microsomal preparations from ox brain was inactivated or diminished in activity by exposure to 2-8m-urea. Similar concentrations of urea diminished the turbidity of the suspensions. 2. Low concentrations (about 2.5mm) of NaATP with the urea gave partial or complete protection of the ATPase, without altering the ...

A new steroidal saponin, 3-{(O-6-deoxy-a-L-mannopyranosyl-(1 --> 4)-O-beta-D-glucopyranosyl-(1 --> 3)-O-[O-beta-D-glucopyranosyl-(1 --> 3)-beta-D-glucopyranosyl-(1 --> 2)]-O-beta-D-glucopyranosyl-(1 --> 4)-beta-D-galactopyranosyl)oxy}-6-hydroxy-(3beta,5alpha,6alpha,25R)-spirostan-12-one, was isolated from Agave brittoniana Trel. The structure was determined by extensive NMR spectroscopy studies...

The activation of the ATPase activity of yeast hexokinase by D-lyxose and D-xylose was investigated. Sugars lacking a carbon 6 activate the ATPase activity while the presence of a carbon 6 inhibits the activity. Xylose and lyxose, which are competitive inhibitors of glucose in the hexokinase reaction, induce substrate inhibition by ATP in the hexokinase and ATPase reactions. Ultracentrifugation...