Adenosine Triphosphate Molecules Research Articles

The Runner: Energy and Endurance

There is much to like about this summary, intended for lay readers, of biochemical factors that control and limit running performance. It contains many fascinating tidbits (eg, 10 20 molecules of adenosine triphosphate are used for each sprint step), and authors provide genuine insights into exercise metabolism. Particularly interesting are their artfully crafted arguments on role of fat metabolism in limiting endurance performance. Despite these basic strengths, however, The Runner is not without its problems. This reviewer found himself frustrated by numerous errors and omissions and flabbergasted by lack of reference citations when data from other researchers are presented. The authors also have a disturbing penchant for presenting their speculations as if they were chiseled in stone at national museum. We are told, for example, that the wall—the extreme fatigue that overtakes marathoners—is caused by limited rate of fatty-acid oxidation. An interesting notion to

Structural studies on metal-ATP complexes: x-ray structures of Mg(II), Ca(II), Mn(II) and Co(II) ternary complexes with ATP and dipyridylamine

The enzyme-catalyzed reactions of transferring simple and substituted phosphoryl groups, such as nucleotidyl groups, are among the most fundamental biochemical processes. Enzymes which utilize one of the nucleotides as a cofactor or substrate usually require a specific complex of the nucleotide with metal ion for activity. The metal ions are involved in a number of mono-, bi- and tri-dentate coordination geometries and some of the forms may be preferred by specific enzymes over the others as substrates. X-ray studies of several metal-polyphosphate compounds have provided a substantial knowledge about modes of interaction between metal ions and phosphoryl groups [1–3]. However, there are only few solid-state studies [4, 5] of metal complexes with adenosine triphosphate (ATP) in spite of the importance for many biochemical reactions. In a previous note we reported the syntheses of a series of ternary complexes between ATP, dipyridylamine (DPA) and the metal ions Mg(II), Mn(II), Co(II), Cu(II) and Zn(II) [6]. Subsequently we prepared ternary complexes with the ions Ca(II), Sr(II), Ba(II), Fe(II), Ni(II), Cd(II) and Pb(II). In order to provide further information about coordination geometry of the metalATP system, the X-ray structure analysis of the ternary complexes Mg(II)ATPDPA (1), Ca(II)ATPDPA (2), Mn(II)ATPDPA (3) and Co(II)ATPDPA (4) has been performed. The compounds were crystallized from solutions containing a mixture of the appropriate components in the molar ratio 1:1:1. All four compounds crystallize in the orthorhombic space group C222 1 (Table I). t001 Some Significant Crystal Data for the M(II)(ATP)(DPA) complexes Mg Ca Mn Co a (Å) 10.233(3) 10.154(3) 10.234(3) 10.218(3) b (Å) 22.734(3) 22.965(3) 22.699(3) 22.717(3) c (Å) 30.997(4) 32.390(4) 31.351(4) 31.027(4) V (Å 3) 7,211.05 7,552.91 7,282.89 7,202.06 Z 8 8 8 8 Diffractometer Philips PW1100 (MoKα) Philips PW1100 (MoKα) Cad-4 (MoKα) Cad-4 (MoKα) No. of observed reflections (F > 3σ(F)) 1050 1200 3534 1850 Some attempts to solve the structures of the compounds (1) and (2) by direct methods, using MULTAN 80 [7] and SHELX 76 [8] packages were unsuccessful. The structures were solved by the SIR program [9] through the extensive use of phase semivariants in the starting set. The structures of the compounds (3) and (4) were independently solved by means of heavy-atom techniques using regular and anomalous Patterson maps. The analysis clearly showed the existence of two different sites occupied by metal ions in the structures. In all four structures the ATP molecule is bonded to one of the metal ions by oxygen atoms from the α-, β- and γ-phosphate groups. There is no bonding interaction between the metal ions and the adenine base. The structure analysis of the compounds (1) and (2) showed the presence of a twofold orientational disorder of the DPA molecules. Further work is in progress to establish the remaining details of the structures.

Active transport of formaldehyde in methanol-utilizing bacteria

Formaldehyde transport experiments were carried out with Pseudomonas C in batch cell-suspension systems in the absence of a growth-supporting carbon source. Direct measurements of extracellular formaldehyde concentrations and indirect measurements of intracellular formaldehyde concentrations were made. Initial transport rates were estimated for different initial formaldehyde concentrations. Adenosine triphosphate (ATP) consumption during formaldehyde transport was noted. Observed was the transport of formaldehyde against its own concentration gradient, along with the depletion of intracellular ATP. A proposed active transport model involving substrate inhibition was shown to be in agreement with the transport rate data. A stoichiometric relationship of three formaldehyde molecules transported per ATP molecule dephosphorylated was calculated from formaldehyde and ATP mass balances.

Biological Energy Transduction

The universal currency of biological energy conversion is the molecule adenosine triphosphate (ATP). Primary energy sources (light, food, etc) are used to synthesise ATP from adenosine diphosphate (ADP) and inorganic phosphate (Pi) – this is the process of phosphorylation.

Two forms of nitrogenase from the photosynthetic bacterium Rhodospirillum rubrum.

Acetylene reduction by nitrogenase from Rhodospirillum rubrum, unlike that by other nitrogenases, was recently found by other investigators to require an activation of the iron protein of nitrogenase by an activating system comprising a chromatophore membrane component, adenosine 5'-triphosphate (ATP), and divalent metal ions. In an extension of this work, we observed that the same activating system was also required for nitrogenase-linked H(2) evolution. However, we found that, depending on their nitrogen nutrition regime, R. rubrum cells produced two forms of nitrogenase that differed in their Fe protein components. Cells whose nitrogen supply was totally exhausted before harvest yielded predominantly a form of nitrogenase (A) whose enzymatic activity was not governed by the activating system, whereas cells supplied up to harvest time with N(2) or glutamate yielded predominantly a form of nitrogenase (R) whose enzymatic activity was regulated by the activating system. An unexpected finding was the rapid (less than 10 min in some cases) intracellular conversion of nitrogenase A to nitrogenase R brought about by the addition to nitrogen-starved cells of glutamine, asparagine, or, particularly, ammonia. This finding suggests that mechanisms other than de novo protein synthesis were involved in the conversion of nitrogenase A to the R form. The molecular weights of the Fe protein and Mo-Fe protein components from nitrogenases A and R were the same. However, nitrogenase A appeared to be larger in size, because it had more Fe protein units per Mo-Fe protein than did nitrogenase R. A distinguishing property of the Fe protein from nitrogenase R was its ATP requirement. When combined with the Mo-Fe protein (from either nitrogenase A or nitrogenase R), the R form of Fe protein required a lower ATP concentration but bound or utilized more ATP molecules during acetylene reduction than did the A form of Fe protein. No differences between the Fe proteins from the two forms of nitrogenase were found in the electron paramagnetic resonance spectrum, midpoint oxidation-reduction potential, or sensitivity to iron chelators.

Nuclear magnetic resonance studies on the self-association of adenosine 5′-triphosphate in aqueous solutions

The self-association of adenosine 5′-triphosphate (ATP) in aqueous, basic solutions has been studied. The results indicate that the monomer–dimer–trimer equilibrium model for base association fits the data well, but so does a model which includes higher order species. This indicates that the ATP molecules in solution can undergo indefinite linear self-association. The average value of the association constant based on the 1H and 31P chemical shift measurements is 0.9 ± 0.3 M−1. Longitudinal relaxation rates for the H8, H1′, and H2 protons of ATP were obtained as a function of the nucleotide concentration. The analysis of the viscosity-corrected proton H2 data yields an association constant of 5.1 ± 1.3 M−1.

Energy dependent changes in the cytochromes of the mitochondrial respiratory chain

In intact mitochondria a stoichiometric coupling exists between cytochrome a 3 and the hydrolysis of adenosine triphosphate (ATP). In each case the modification of one cytochrome a 3 (measured as a spectral change) is coupled to the hydrolysis of one ATP molecule. When both cytochromes a 3 and a are reduced the measured equilibrium constant is 0.06 m −1 but this constant is 10 3 M −1 when both cytochromes are oxidized. When the sixth ligand for cytochrome a 3 is an externally added ligand (HCN, H 2S, CO, NO) the equilibrium constant is different for each ligand, suggesting that the ATP induced modification is of the fifth ligand but that it is energetically dependent on the chemical nature of the sixth ligand. The measured half-reduction potentials for cytochromes a 3 and b T are dependent on the concentrations of added ATP, adenosine diphosphate (ADP), and orthophosphate. The relationship is consistent with a ligand exchange mechanism in which the ligand on the cytochrome is dependent on the phosphate potential ( ATP ADP × P i). The equilibrium constants obtained by the ligand exchange treatment of the E m values for cytochrome a 3 are consistent with those obtained by direct measurement of the equilibrium constants for the spectrally measured changes.

Immunochemical determination of the molecular conformation of nucleotides

Rabbit gamma globulin anti-adenosine monophosphate-egg albumin (AMP-EA) was used to study the molecular conformation of nucleotides such as adenosine triphosphate (ATP) or adenosine diphosphate (ADP). The study was done uisng AMP, ADP, and ATP, under different conditions, to inhibit the precipitin reaction between AMP-human serum albumin (HSA) and anti-AMP-EA. When the haptens were dissolved in 0·15 M saline at pH 7·0, the best inhibitor was AMP followed by ADP and then by ATP. If the haptens were dissolved in 0.02 M disodium ethylene diamino tetra-acetate (EDTA)-0.15· M saline at pH 7·0, the inhibition by AMP was not modified but both ADP and ATP inhibited as well as AMP. Finally if the haptens were dissolved in 0·02 M MgCl 2-0·15 M saline at pH 7·0, again AMP inhibited as before but ADP and ATP inhibited less than wehn dissolved in saline alone. ATP in saline or with magnesium ions (Mg ++) inhibited less than ADP in the same conditions. These results indicate that ADP and ATP have a folded molecular conformation with Mg ++ participating in it in such a way that antibodies specific for the adenine base cannot react with them as well as with AMP which does not have this folded configuration. EDTA removes the Mg ++, causing an unfolding of the ATP or ADP molecule and facilitating in this way their reaction with anti-AMP antibodies in the same manner as with AMP alone.

Effects of starvation on normal development of -hydroxybutyrate dehydrogenase activity in foetal and newborn rat brain.

THE mitochondrial enzyme β-hydroxybutyrate dehydrogenase (BDH) catalyses the conversion of β-hydroxybutyrate to acetoacetate, with the subsequent production of three molecules of adenosine triphosphate for every molecule of β-hydroxybutyrate oxidized. Recent evidence suggests that this energy-yielding reaction is important for maintaining the metabolism of the brain when the supply of glucose is chronically depleted. Owen et al.1 demonstrated that β-hydroxybutyrate and acetoacetate become the principal sources of energy for the brain in humans subjected to prolonged starvation. The transition from glucose to ketones as the primary substrate for oxidative metabolism in the central nervous system occurs without demonstrable cerebral dysfunction1.

Parameters of rumen fermentation in a continuously fed sheep: evidence of a microbial rumination pool.

The feed and feces of a continuously fed sheep were analyzed for carbon, hydrogen, and nitrogen, with oxygen as the remainder. The daily feed-feces weight difference was used as the reactant in an equation representing the rumen fermentation. The measured products were the daily production of volatile fatty acids (VFA), CH(4), CO(2), and ammonia. The carbon unaccounted for was assumed to be in the microbial cell material produced in the rumen and absorbed before reaching the feces. The ratio of C to H, O, and N in bacteria was used to represent the elemental composition of the microbes formed in the rumen fermentation, completing the following equation:C(20.03)H(36.99)O(17.406)N(1.345) + 5.65 H(2)O --> C(12)H(24)O(10.1) + 0.83 CH(4) VFA + 2.76 CO(2) + 0.50 NH(3) + C(4.44)H(8.88)O(2.35)N(0.785) microbial cells absorbed With C arbitrarily balanced and O balanced by appropriate addition of water, any error is reflected in the H. The H recovery was 98.5%. The turnover rate constant for rumen liquid equilibrating with polyethylene glycol (PEG) was 2.27 per day. Direct counts and volume measurements of the individual types of bacteria and protozoa in the rumen were used to calculate the total microbial cell volume in the rumen, not equilibrating with it. The dry matter in the rumen (582 g) and the nitrogen content (12.05) of the microbes in the rumen were estimated, the latter constituting 85% of the measured N in the rumen. Calculations for rumen dry matter and nitrogen turning over at the PEG rate introduce big discrepancies with other parameters; a rumination pool must be postulated. Its size and composition are estimated. Arguments are presented to support the view that dry matter and some of the microbes, chiefly the protozoa, do not leave the rumen at the PEG rate. One experiment with the same sheep fed twice daily showed significantly less production of microbial cells than did the continuous (each 2 hr) feeding. Analysis of the microbial cell yield suggests that, on the basis of 11 mg of cells per adenosine triphosphate molecule, a maximum of six adenosine triphosphate molecules could have been formed from each molecule of hexose fermented.

Parameters of Rumen Fermentation in a Continuously Fed Sheep: Evidence of a Microbial Rumination Pool

The feed and feces of a continuously fed sheep were analyzed for carbon, hydrogen, and nitrogen, with oxygen as the remainder. The daily feed-feces weight difference was used as the reactant in an equation representing the rumen fermentation. The measured products were the daily production of volatile fatty acids (VFA), CH(4), CO(2), and ammonia. The carbon unaccounted for was assumed to be in the microbial cell material produced in the rumen and absorbed before reaching the feces. The ratio of C to H, O, and N in bacteria was used to represent the elemental composition of the microbes formed in the rumen fermentation, completing the following equation:C(20.03)H(36.99)O(17.406)N(1.345) + 5.65 H(2)O --> C(12)H(24)O(10.1) + 0.83 CH(4) VFA + 2.76 CO(2) + 0.50 NH(3) + C(4.44)H(8.88)O(2.35)N(0.785) microbial cells absorbed With C arbitrarily balanced and O balanced by appropriate addition of water, any error is reflected in the H. The H recovery was 98.5%. The turnover rate constant for rumen liquid equilibrating with polyethylene glycol (PEG) was 2.27 per day. Direct counts and volume measurements of the individual types of bacteria and protozoa in the rumen were used to calculate the total microbial cell volume in the rumen, not equilibrating with it. The dry matter in the rumen (582 g) and the nitrogen content (12.05) of the microbes in the rumen were estimated, the latter constituting 85% of the measured N in the rumen. Calculations for rumen dry matter and nitrogen turning over at the PEG rate introduce big discrepancies with other parameters; a rumination pool must be postulated. Its size and composition are estimated. Arguments are presented to support the view that dry matter and some of the microbes, chiefly the protozoa, do not leave the rumen at the PEG rate. One experiment with the same sheep fed twice daily showed significantly less production of microbial cells than did the continuous (each 2 hr) feeding. Analysis of the microbial cell yield suggests that, on the basis of 11 mg of cells per adenosine triphosphate molecule, a maximum of six adenosine triphosphate molecules could have been formed from each molecule of hexose fermented.

Yields of Hydrogenomonas eutropha from growth on succinate and fumarate.

Molar growth yields were determined from chemostat cultures of Hydrogenomonas eutropha on succinate and on fumarate. The yields from culture on succinate were about 12 g higher than on fumarate. Assuming this difference to be equivalent to 1 molecule of adenosine triphosphate, it is concluded that the oxidation by oxygen of the Hydrogenomonas cytochrome b yields 1 molecule of adenosine triphosphate.

The stoicheiometry of the sodium pump.

1. When resealed ghosts containing adenosine triphosphate (ATP), magnesium and sodium were incubated in a medium containing potassium, ATP was hydrolysed vigorously by a ouabain-sensitive mechanism. If the ghosts contained potassium instead of or in addition to sodium, and the external solution contained sodium but no potassium, there was little ouabain-sensitive hydrolysis of ATP. As it is known that the ouabain-sensitive ATPase in fragmented ghosts requires both sodium and potassium ions, these results show that the ATPase is activated by potassium externally and by sodium internally, and suggest that the ions activating the ATPase are the ions that are transported.2. Resealed ghosts containing ATP, magnesium and sodium were incubated in sodium-free media containing potassium, with and without ouabain, and the rate of loss of sodium and rate of hydrolysis of ATP were measured. The hydrolysis of 1 molecule of ATP by the ouabain-sensitive mechanism was accompanied by the ouabain-sensitive loss of about 3 sodium ions.3. (24)Na and (42)K were used to measure sodium efflux and potassium influx in identical batches of fresh red cells under the same conditions and at the same time. Each flux was measured in the presence and absence of ouabain. The ratio (ouabain-sensitive sodium efflux)/(ouabain-sensitive potassium influx) was significantly greater than 1 (1.20 +/- 0.01 and 1.35 +/- 0.01 in two experiments). If a small fraction of the potassium influx represented a ouabain-sensitive potassium: potassium exchange, the ratio of the numbers of ions moved in the sodium: potassium exchange catalysed by the pump must have been even further from unity.4. Resealed ghosts containing [gamma-(32)P]ATP, magnesium, (24)Na and orthophosphate were incubated in balanced salt solutions with and without potassium and with and without ouabain. A comparison of sodium efflux, estimated from (24)Na loss, with ATP hydrolysis, estimated from the formation of [(32)P]orthophosphate, showed that the sodium:sodium exchange in a potassium-free medium was accompanied by little or no ouabain-sensitive hydrolysis of ATP.5. Experiments on intact red cells loaded with (24)Na showed that both sodium:sodium exchange in a potassium-free medium, and sodium:potassium exchange in a medium containing potassium, were partially inhibited by oligomycin (1-10 mug/ml.). Inhibition of the sodium:potassium exchange was not affected by raising the external potassium concentration.

Electrical potential across the rat small intestine stimulated by adenosine triphosphate.

TRANSPORT processes in the small intestine are dependent on energy which suggests the participation, directly or indirectly, of adenosine triphosphate (ATP). No evidence has, however, been produced that exogenous ATP can influence intestinal transport processes, which may well result from the difficulty of getting the unstable ATP molecule to the correct place in the cellular organization before its hydrolysis occurs. A way around this difficulty is offered by the study of electrical potentials in the intestine, which are known to be associated with intestinal transfer of various substances. Potential changes can be measured within a few minutes of setting up the intestinal preparation, and appear within seconds after addition of transferable substances. They therefore appear to offer an ideal method for studying the effect of ATP on intestinal transfer.

Adenosine triphosphate usage by flagella.

Comparison of beat frequencies with rates of dephosphorylation of adenosine triphosphate by glycerinated sea urchin spermatozoa as functions of adenosine triphosphate concentration suggests that each molecule of the flagellar adenosine triphosphatase, dynein, dephosphorylates one adenosine triphosphate molecule during each beat cycle.

Driving the sodium pump backwards to form adenosine triphosphate.

IF the ionic pump in the red cell membrane expels three sodium ions and takes up about two potassium ions for each molecule of adenosine triphosphate (ATP) hydrolysed1–5, under physiological conditions the free energy available to drive the reaction forwards must be quite small—about 3,000 cal. By arranging that the concentration gradients for sodium and potassium are even more adverse, it should be thermodynamically possible to run the pump backwards and synthesize ATP, though, of course, theory cannot predict that the reaction would occur at a measurable rate. Investigators who have looked for ATP–inorganic phosphate (Pi) exchange associated with “transport ATPase” activity6,7 have never found it, but they have always looked in broken cell preparations where ionic concentrations must be the same on both sides of the membrane and where, in consequence, the free energy change for the overall reaction is likely to be heavily in favour of ATP breakdown. An ingenious attempt to reverse the sodium pump in perfused squid axons failed, but it failed in such a way as to leave the possibility of reversal still an open question8. More encouraging was the finding that red cells with intact membranes show peculiar behaviour when placed in solutions lacking potassium, and the effect of internal phosphate concentration on this behaviour suggests that the final stage of ATP hydrolysis—Pi release—may be reversible9.