Adenosine triphosphatase function

Bragg, P.D., and Hou, C. (1975) Subunit composition, function, and spatial arrangement in the Ca2+-and Mg2+-activated adenosine triphosphatases of Escherichia coli and Salmonella typhimurium. Arch. Biochem. Biophys. 167, 311-321. 

Boldyrev, A.A. (1979). The role of lipids in the function of Na,-K-activated adenosine triphosphatase (In Russian). Biologicheskii Nauki 1979 (3), 5-17. 

Alkaline phosphatase, acid phosphatase, 5 -nucleotidase, monoacyl hydrolase, ribonuclease, type 1 phosphodiesterase, adenosine triphosphatase, adenyl cyclase, glycosyl transferase, esterases and disaccharidase have been biochemically or cytochemically demonstrated in the tegument of various cestodes (152, 210, 250, 374, 491, 620, 624-626, 651, 718, 763, 776, 898). Several of these enzymes - phosphatases, 5 -nucleotidase and phosphodiesterase - probably have a digestive and/or absorptive function but the role of the others is uncertain. 

The precise mechanism whereby digoxin produces a toxic effect may involve inhibition of Na K -activated adenosine triphosphatase, an enzyme that plays a vital role in maintaining normal cone receptor function.This would explain the drug-induced interference with both dark adaptation and color vision. 

Scarff K L, Judd L M, Toh B H et al 1999 Gastric H(+), K(+)-adenosine triphosphatase beta subunit is required for normal function, development and membrane structure of mouse parietal cells. Gastroenterology 117 605-618... 

As with other cyclodiene insecticides, heptachlor blocks the neuronal uptake of chloride ions by blocking the activity of y-aminobutyric acid. This results in only a partial repolarization of activated neurons leading to an uncontrolled excited condition. Additionally, chlordane inhibits Ca, Mg -adenosine triphosphatase (ATPase) and Na,K-ATPase functions, leading to increased concentrations of... 

Thallium s mechanism of toxicity is related to its ability to interfere with potassium ion functions. Thallium interferes with energy production at essential steps in glycolysis, the Kreb s cycle, and oxidative phosphorylation. Other effects include inhibition of sodium-potassium-adenosine triphosphatase and binding to sulfhydryl groups. 

Brown AH, Niles NR, Braimbridge MV, Austen WG (1972) The combination of adenosine-triphosphatase inhibition and provision of high-energy phosphates for the preservation of unperfused myocardium, assessed by ventricular function, histology and birefringence. J Cardiovasc Surg 13 602-616... 

Caldesmon is a cytoplasmic protein with two isoform classes, one of which is found predominantly in smooth muscle cells and other cell types with partial myogenic differentiation. High-molecular-weight isoforms with molecular weights between 89 and 93 kD are capable of binding to actin, tropomyosin, calmodulin, myosin, and phospholipids, and they function to counteract actin-tropomyosin-activated myosin adenosine triphosphatase (ATPase). As such, they are mediators for the inhibition of calcium-dependent smooth muscle contraction." ... 

Enzymes having metals as their components can also be inhibited by a substitution of one of these metal ions by another ion with the same charge and a similar size. For example, the toxic effect of cadmium is due to a substitution for zinc, which is a common component in metalloenzymes. The Zn " " and Cd ions are chemically similar, however, the cadmium-containing enzyme does not function properly. The Cd " ions can result, for instance, in the inhibition of amylase, adenosine triphosphatase, adcohol dehydrogenase, glutamic-oxalacetic transaminase, carbonic anhydrase and peptidase activity in carboxypeptidase [4]. 

Chlorine is well studied for its biological, and especially for, its electrolyte significance. It is essential for almost every organism and likely has a catalytic function. It is moderately toxic to mammals when injected intravenously, otherwise it is relatively harmless. It has received intense attention because of its well-known essentiality, but its topographical distribution in the human brain is less known. Significantly decreased chlorine-adenosine-triphosphatase (Cl-ATPase) activity has been reported 1998 in AD brains, compared to age-matched controls (Hattori et ai, 1998). 

Heat shock proteins (Hsp), stress-response proteins, a group of highly conserved proteins in both prokaryotes and eukaryotes, formed in response to hyperthermia or other noxious conditions. Almost all Hsp function as molecular chaperones. According to their molecular weight (in kDa), the Hsp are divided into six main families. (1) HsplOO belongs to the AAA + protein super family (adenosine triphosphatases with diverse activities) sharing a common... 

Very few data are available with regard to metabolism of palytoxin in the animal/human body and its connection with toxicity. The main mode of palytoxin action (which is presented in detail in Chapter 34) is related to disruption of the mammahan cell sodium pump functionality. Targeting the Na, K -adenosine triphosphatase (ATPase) pump, palytoxin binds to the ATPase and converts the pump into a nonspecific ion channel, thereby, short-circuiting membrane function of the cell and eventually causing cell lysis [64]. 

The effects of ouabain on a sodium and potassium dependent adenosine triphosphatase (Na,K-ATPase) were studied on heart enzymes isolated from a number of mammalian species. Ouabain inhibition in vitro was correlated with in vivo changes in heart and enzyme function at doses lower than those necessary to induce toxicity and arrhythmias. ... 

This enzyme activity has been observed in myosin and actomyosin, mitochondria, microsomes, and cell membranes. In some cases magnesium ions function as an activator, in others calcium ions, and in still others, both calcium and magnesium are requited. Another form of adenosine-triphosphatase is stimulated by sodium and potassium ions and is inhibited by ouabain. Some forms of the enzyme can hydrolyse inosine triphosphate and other nucleoside-5 -triphosphates. The substrate specificity may depend upon the activating divalent cation and on the presence of monovalent cations. These enzymes are probably important components of a system responsible for facilitating cation transfer in membranes. They should not be confused with adenosine triphosphate pyrophosphatase E.C. 3.6.1.8. 

In order to function, some enzymes require a metal (such as calcium), or a nonmetal, or both, attached to them, either loosely or tightly others function independently. For example, calcium activates a number of enzymes including pancreatic lipase, adenosine triphosphatase, and some proteolytic enzymes. 

Cadmium inhibited rat brain s3maptosomal adenosine triphosphatase activity in vitro and was more potent in this respect than aluminum or manganese. All three metals reduced the uptake of choline, catecholamines, y-amino butyric acid, and glutamic acid by rat brain synaptosomes. Cadmium ions interfere with membrane function in rat brain synaptosomes by inhibiting the methylation of phospholipids. Cadmium has been found to be a much more potent inhibitor in this respect than aluminum or manganese. ... 

Vol. II, Balaban Intern. Sci. Serv., Philadelphia, pp. 945-954 Sone N, Yoshida M, Hirata H and Kagawa Y (1977) Reconstitution of vesicles capable of energy transformation from phospholipids and adenosine triphosphatase of a thermophilic bacterium, J. Biochem. 81, 519-528 Williams RIP (1961) Possible functions of chains of catalysts, J. Theor. Biol. 1, 1-13... 

---