Search results for "adenosine triphosphate"

Conversion of the Ca2+-ATPase from Rhodospirillum rubrum into a Mg2+-dependent enzyme by 1,N6-etheno ATP

1980

Nucleoside triphosphate hydrolysis of R.rubrum ATPase complexes can be changed from Ca2+-dependence to Mg2+-dependence by replacing ATP with 1,N6-etheno ATP. Four ATPase complexes which have been prepared by different procedures hydrolyze ATP and 1,N6-etheno ATP at different rates in dependence on the added metal ions. These differences allow an easy distinction of the various enzyme forms.

Metabolic shift of polyphosphate-accumulating organisms with different levels of polyphosphate storage

2012

Previous studies have shown that polyphosphate-accumulating organisms (PAOs) are able to behave as glycogen-accumulating organisms (GAOs) under different conditions. In this study we investigated the behavior of a culture enriched with Accumulibacter at different levels of polyphosphate (poly-P) storage. The results of stoichiometric ratios Gly degraded/HAc uptake, PHB synthesized/HAc uptake, PHV synthesized/HAc uptake and P release/HAc uptake confirmed a metabolic shift from PAO metabolism to GAO metabolism: PAOs with high poly-P content used the poly-P to obtain adenosine tri-phosphate (ATP), and glycogen (Gly) to obtain nicotinamide adenine dinucleotide (NADH) and some ATP. In a test whe…

Modeling ATP protonation and activity coefficients in NaClaq and KClaq by SIT and Pitzer equations.

2006

Abstract The acid–base properties of Adenosine 5′-triphosphate (ATP) in NaCl and KCl aqueous solutions at different ionic strengths (0  I  / mol L − 1  ≤ 5 for NaCl aq , 0  I  / mol L − 1  ≤ 3 for KCl aq ) and at t  = 25 °C were investigated. A selection of literature data on ATP protonation constants and on activity isopiestic coefficients was performed, together with new potentiometric measurements (by ISE-H + , glass electrode). Both literature and new experimental data were used to model the dependence on ionic strength and ionic medium of ATP protonation by SIT (Specific ion Interaction Theory) and Pitzer equations. In addition to values of first and second ATP protonation constants in…

Novel mutations of the MET proto-oncogene in papillary renal carcinomas.

1999

Hereditary papillary renal carcinoma (HPRC) is characterized by multiple, bilateral papillary renal carcinomas. Previously, we demonstrated missense mutations in the tyrosine kinase domain of the MET proto-oncogene in HPRC and a subset of sporadic papillary renal carcinomas. In this study, we screened a large panel of sporadic papillary renal carcinomas and various solid tumors for mutations in the MET proto-oncogene. Summarizing these and previous results, mutations of the MET proto-oncogene were detected in 17/129 sporadic papillary renal carcinomas but not in other solid tumors. We detected five novel missense mutations; three of five mutations were located in the ATP-binding region of t…

Nested MWC model describes hydrolysis of GroEL without assuming negative cooperativity in binding

2002

Folding assistance and ATPase activity of GroEL are based on the existence of different conformations. In order to characterise these conformations, published data on steady state ATPase activity in the absence of GroES were reanalysed simultaneously in terms of the Nested MWC model. This model is a hierarchical extension of the symmetry-model of Monod et al. [J. Mol. Biol. 12 (1965) 88]. An unique set of GroEL specific parameters was obtained. This set was supported by comparison of predictions arising from this set of values with experimental data for hydrolysis of ATP in the presence of ADP and ATPgammaS, binding of ATPgammaS and ADP to GroEL in the absence of ATP, and binding of ATP as …

Membrane-Bound F1 ATPase from Micrococcus Sp. ATCC 398E. Purification and Characterization by Affinity Chromatography

1976

A chemically reactive ATP analogue, 6-[(3-carboxy-4-nitrophenyl)thio]-9-β-D-ribofuranosylpurine 5′-triphosphate (Nbs6ITP) has been synthesized. It has the ability to form stable thioether bonds between the 6-position of the purine ring and aliphatic mercapto groups. The nucleotide moiety of the reagent has been covalently bound to agarose, via iminobispropylamine and N-acetyl-homocysteine as spacer with the purpose of producing an affinity chromatography material. The affinity matrix binds solubilized F1 ATPase from a crude extract of Micrococcus sp. membranes. Afterwards the enzyme can be selectively eluted from the column at a defined ATP concentration. This method is superior to the conv…

Flying insects: model systems in exercise physiology

1996

Insect flight is the most energy-demanding exercise known. It requires very effective coupling of adenosine triphosphate (ATP) hydrolysis and regeneration in the working flight muscles.31P nuclear magnetic resonance (NMR) spectroscopy of locust flight muscle in vivo has shown that flight causes only a small decrease in the content of ATP, whereas the free concentrations of inorganic phosphate (P i ), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) were estimated to increase by about 3-, 5- and 27-fold, respectively. These metabolites are potent activators of glycogen phosphorylase and phosphofructokinase (PFK). Activation of glycolysis by AMP and P i is reinforced synergistica…

Pharmacological analysis of intrinsic neural control of rat duodenum motility in vitro

1988

Biokinetisches Verhalten und Stoffwechselwirkungen von Fructose bei hochdosierter Dauerinfusion an der Ratte

1976

The steady-state blood level of fructose during 24 hours intravenous infusion in response to different doses follows saturation kinetics. Even after toxic doses of 1.5 g/kg/h no depletion of liver adenine nucleotides can be observed after 24 hours. In the kidneys, however, ATP, ADP and total adenine nucleotides were decreased after a dose of 1.5 g/kg/h of fructose. The blood glucose increased continuously at infusion rates of 1.5 g/kg/h. Inorganic phosphate in the blood increased at doses of 1.0 and 1.5 g/kg/h. The weight of the kidneys increased, presumably through water uptake. Urinary secretion was drastically reduced at doses above 1.0 g/kg/h. An appreciable activity of ketohexokinase c…

CD73-generated extracellular adenosine in chronic lymphocytic leukemia creates local conditions counteracting drug-induced cell death

2011

Abstract Extracellular adenosine (ADO), generated from ATP or ADP through the concerted action of the ectoenzymes CD39 and CD73, elicits autocrine and paracrine effects mediated by type 1 purinergic receptors. We have tested whether the expression of CD39 and CD73 by chronic lymphocytic leukemia (CLL) cells activates an adenosinergic axis affecting growth and survival. By immunohistochemistry, CD39 is widely expressed in CLL lymph nodes, whereas CD73 is restricted to proliferation centers. CD73 expression is highest on Ki-67+ CLL cells, adjacent to T lymphocytes, and is further localized to perivascular areas. CD39+/CD73+ CLL cells generate ADO from ADP in a time- and concentration-dependen…