Triphosphatases and

Matkovits T, Christakos S. 1995. Variable in vivo regulation of rat vitamin D-dependent genes (osteopontin, Ca, Mg-adenosine triphosphatase, and 25-hydroxyvitamin D3 24-hydroxylase) implications for differing mechanisms of regulation and involvement of multiple factors. Endocrinology 136 3971-3982. 

Voluntary muscles contain a variety of fibre types which are specialized for particular tasks. Most muscles contain a mixture of fibre types although one type may predominate. All human skeletal muscles are composed of several different muscle fibre types. Up to seven different fibre types have been identified histochemically based on the pH stability of myofibrillar adenosine triphosphatase and on the myosin heavy chain profile. Innumerable fibre type transients exist due to continuing adaptation processes. However, three main... 

By the use of histochemical techniques and immunoelectrophoresis, Nielsen and Bjerrum (1977) identified four major protein complexes in milk lipid globule membrane. They found that xanthine oxidase was located on the internal face of the membrane and that the other three complexes, as well as Mg2+-adenosine triphosphatase and 5 -nucleo-tidase, were accessible on the outer surface of the membrane. Based on available information, it cannot be determined if any proteins of the globule membrane span the lipid bilayer, as do certain proteins of other membranes (Singer 1974 Rothman and Lenard 1977). 

M. Szymona and T. Szumilo (1966). Adenosine triphosphatase and inorganic polyphosphate-fructokinases of Mycobacterium phlei. Acta Biochim. Pol., 13, 129-134. 

Some of the enzymes of the MFGM, such as 5 -nucleotidase, adenosine triphosphatase and phosphodiesterase I, are known to be enriched in plasma membranes. However, other enzymes found in the MFGM are known constituents of intracellular membranes or are cytosolic. Why some of these are present in the MFGM remains to be explained some may possibly originate from material entrained in cytoplasmic crescents and therefore are not true MFGM constituents. Perhaps some enzymes become... 

The effect on lOP of the cardiac glycosides, primarily digitaUs derivatives and ouabain, has been of interest for many years. The physiologic effects of these agents are produced by their ability to inhibit Na+K+ adenosine triphosphatase, and a ouabain-sensitive Na+K+ adenosine triphosphatase has been demonstrated in the ciliary epitheUum. In the ciliary nonpigmented epithelium, as in other types of secretory epitheUum, Na+K+ adenosine triphosphatase is thought to be responsible for the active transport of sodium, a process necessary for aqueous secretion to occur. 

Adenylate cyclase has been obtained in soluble form from bacteria [12,13], and can be prepared free of contaminating phosphodiesterase, ATPase (adenosine triphosphatase) and pyrophosphatase activities, but the relationship of the bacterial enzyme to the enzyme found in higher forms of life is not yet clear. The bacterial enzyme, for example, does not respond to mammalian hormones or sodium fluoride. 

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. 

Clawson, G. A., Woo, C. H., and Smuckler, E. A., Independent responses of nucleoside triphosphatase and protein kinase activities in nuclear envelope following thioacetamide treatment, Biochem. Biophys. Res. Commun., 95[3], 1200, 1980. 

Another mode of protein-electric field interaction has been proposed by Blank (18-21). Blank considers that the effects of an electric field on membrane protein mainly arise from its effect on the electric double layer at the water-membrane interface. In other words, an electric field can change the concentration of ions near a membrane protein, which results in a stimulation or a reduction in its activity. The surface compartmental model has been used to interpret the ac stimulated adenosine triphosphate (ATP) splitting of Na, K-ATPase (adenosine triphosphatase) and ribonucleic acid (RNA) synthesis in various types of cells (19-21). 

The proteins of membranes often include enzymes (e.g. adenosine triphosphatase), and permeases (Section 2.1) are commonly found in membranes. It is logical to suppose that the protruding parts of the membrane proteins are made mainly of amino acids with j o/ar side-chains, whereas the embedded parts are rich in amino acids with non-polar side-chains. 

K. Atterwill, D. J, Atkinson, I. Bermudez, and R. Balazs, Effect of thyroid hormone and serum on the development of Na+,K+-adenosine triphosphatase and associated ion fluxes in cultures from rat brain. Neuroscience 14 361-373 (1985),... 

The Pd-catalyzed cascade Heck reaction of 5-methylenecycloheptene precursor 108 was utilized to construct the scopadulan ring system and chiral centers at C9 and C12 of the bicyclo-octane 109 and 110 for the first total synthesis of scopadulcic acid B, which is a powerful inhibitors of H+, K+ -adenosine triphosphatase and have potential for the treatment of peptic ulcers, gastritis, and esophagitis. (Scheme 55) (103,104). 

Finally, it should be pointed out that a number of other phosphohydrolases such as myosin ATPase, nucleoside triphosphatases, and acid or alkaline phosphatases have been shown to catalyse the hydrolysis of ThTP with variable but low degree of efficiency. Two different enzymes hydrolysing ThTP have been reported in E. coli, but they have not been characterized. 

The catalytic domains of human 25 kDa hThTPase and CyaB-like adenylyl cyclase from Aeromonas hydrophilia define a novel superfamily of domains that should bind organic phosphates (Iyer and Aravind 2002). This superfamily of proteins was therefore called CYTH (CYaB-THiamin triphosphatase), and the presence of orthologs was demonstrated in all three superkingdoms of life. This suggested that CYTH is an ancient enzymatic domain and that a representative must have been present in the last universal common ancestor (LUCA) of all extant life forms. It appears that the CYTH superfamily includes enzymes with various catalytic properties (adenylyl cyclase or inorganic triphosphatase in some bacteria, RNA triphosphatase in yeast, ThTPase in animals) but with important common features ... 

Iyer, L.M., and Aravind, L., 2002. The catalytic domains of thiamine triphosphatase and CyaB-like adenylyl cyclase define a novel superfamily of domains that bind organic phosphates. BMC Genomics. 3 33. 

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. 

Padykula HA, Herman B. (19 5 5) Factors affecting the activity of adenosine triphosphatase and other phosphatases as measured by histochemical techniques. J Histochem Cytochem 3, 161-169. 

A low intake of magnesium may also contribute to a higher mortality of cardiovascular disease in soft water areas. Magnesium -and also calcium - are involved in enzyme systems in the heart muscle. Sealig (1972) (54) has shown for example that inadequate magnesium concentration interferes with the activation of adenosin-triphosphatase and causes a loss of potassium by myocardial cells. This might be responsible for sudden death from coronary artery disease. 

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