Adenosine triphosphate

Abstract: The alpha- and beta-subunits of membrane-bound ATP synthase complex bind ATP and ADP: beta contributes to catalytic sites, and alpha may be involved in regulation of ATP synthase activity. The sequences of beta-subunits are highly conserved in Escherichia coli and bovine mitochondria. Also alpha and beta are weakly homologous to each other throughout most of their amino acid sequences, suggesting that they have common functions in catalysis. Related sequences in both alpha and beta and in other enzymes that bind ATP or ADP in catalysis, notably myosin, phosphofructokinase, and adenylate kinase, help to identify regions contributing to an adenine nucleotide binding fold in both ATP synthase subunits.

Abstract: This is a record of the concentrations of the nonenzyme components of the Embden-Meyerhof system in mouse brain measured at brief intervals after the production of complete ischemia by decapitation. All of the 18 recognized active components were looked for. Of these, 1,3-diphosphoglycerate did not reach levels measurable by the procedures used. Additional substances determined were glycogen, phosphocreatine, creatine, adenosine 5’-phosphate, cu-glycerophosphate, and triphosphopyridinenucleotide and its reduced form. The pyridine nucleotide values are only provisional. Considerable attention is devoted to methodology, since there are numerous possibilities for serious errors in preparation of samples as well as in the analyses for individual substrates. The substances measured account for all the known significant sources of energy available to the brain after its blood supply is cut off. Therefore it is possible to calculate the metabolic rate during the brief period of survival, as well as the time sequence according to which the brain taps its reserve sources of energy. Ischemia resulted in increases in glycolytic rates of at least 4to 7-fold in different experimental groups of mice. The coincident changes in substrate concentrations show which steps were facilitated to make this increase in flux take place, i.e. which steps control glycolysis in brain. These steps are the phosphorylations of glucose and fructose 6-phosphate, and the phosphorolysis of glycogen. There is no evidence that facilitation occurs at any other step in the glycolytic pathway.

Abstract: Apoptosis and necrosis are considered conceptually and morphologically distinct forms of cell death Here, we report that demise of human T cells caused by two classic apoptotic triggers (staurosporin and CD95 stimulation) changed from apoptosis to necrosis, when cells were preemptied of adenosine triphosphate (ATP) Nuclear condensation and DNA fragmentation did not occur in cells predepleted of ATP and treated with either of the two inducers, although the kinetics of cell death were unchanged Selective and graded repletion of the extramitochondrial ATP/pool with glucose prevented necrosis and restored the ability of the cells to undergo apoptosis Pulsed ATP/depletion/repletion experiments also showed that ATP generation either by glycolysis or by mitochondria was required for the active execution of the final phase of apoptosis, which involves nuclear condensation and DNA degradation

Abstract: A method is described for preparing /sup 32/P-labeled ATP of high specific activity by an excbange reaction The method is simple and requires only substrates and enzymes that are available commercially Hydrolysis of the labeled ATP with heavy meromyosin indicates that 98 to 99% of the /sup 32/P is in the 1 -phosphate group (auth)