scholarly journals The free energy change associated with the hydrolysis of the thiol ester bond of acetyl coenzyme A

1955 ◽  
Vol 59 (1) ◽  
pp. 44-46 ◽  
Author(s):  
K. Burton
Keyword(s):  
Free Energy ◽  
Coenzyme A ◽  
Free Energy Change ◽  
Energy Change ◽  
Ester Bond ◽  
Acetyl Coenzyme A ◽  
Thiol Ester ◽  
Acetyl Coenzyme ◽  
Hydrolysis Of

scholarly journals Folate-dependent hydrolysis of acetyl-coenzyme A by recombinant human and rodent arylamine N-acetyltransferases

2015 ◽  
Vol 3 ◽  
pp. 45-50 ◽  
Author(s):  
Marcus W. Stepp ◽  
Galina Mamaliga ◽  
Mark A. Doll ◽  
J. Christopher States ◽  
David W. Hein
Keyword(s):  
Coenzyme A ◽  
Acetyl Coenzyme A ◽  
Acetyl Coenzyme ◽  
Hydrolysis Of

ATP-Dependent Synthetases and Ligases

2007 ◽  
Author(s):  
Perry A. Frey ◽  
Adrian D. Hegeman
Keyword(s):  
Free Energy ◽  
Ethyl Acetate ◽  
Reaction Mechanisms ◽  
Standard Free Energy ◽  
Free Energy Change ◽  
Energy Change ◽  
Free Energy Barrier ◽  
Standard Free Energy Change ◽  
Face To Face ◽  
Hydrolysis Of

The joining of two molecules is energetically unfavorable in an aqueous medium when the substrates correspond to hydrolysis products. In biochemistry, such ligations are driven by the free energy released by the hydrolysis of MgATP or an energetically equivalent molecule. The ATP-dependent synthetases and ligases catalyze reactions in which water is extracted from two molecules that become joined. The amount of free energy available depends on the site at which the ATP molecule is cleaved. The most common cleavage modes and the free energy change under standard conditions, which are pH = 7.0, 25°C, and 1 mM free Mg2+, are given in (Alberty, 1994; Arabshahi and Frey, 1995). Hydrolysis of the α,β-phosphoanhydride linkage to form AMP and PPi releases 3.2 kcal mol–1 more free energy than hydrolysis of the β,γ-linkage. In the actions of ATP-dependent ligases and synthetases, the free energy released in the hydrolysis of MgATP is used to overcome the energetic barrier to the elimination of water. The general principle is exemplified by the free energy barrier for the formation of ethyl acetate from acetate and ethanol under standard conditions, which is ΔG' = +4 kcal mol−1 (Jencks and Regenstein, 1970) The free energy change in the hydrolysis of MgATP to MgADP and Pi is ΔG' = –7.7 kcal mol−1 under the same conditions (Alberty, 1994). If these two reactions can be made to be interdependent, or coupled, the overall process would be the reaction of acetate, ethanol, and ATP to produce ethyl acetate, MgADP, and Pi, and the overall standard free energy change would be ΔG' = –3.7 kcal mol−1, making it a spontaneous or energetically downhill process. In the action of an ATP-dependent synthetase or ligase, the enzyme links the hydrolysis of MgATP with the ligation of the molecules by catalyzing the phosphorylation or adenylylation of one substrate and then the displacement of phosphate or AMP by the other substrate. Two types of glutamine synthetases are found in bacteria and eukaryotes. The bacterial glutamine synthetases, designated GS I (EC 6.3.1.2), are the most thoroughly studied. All species of GS I are dodecameric, 600- to 640-kDa enzymes assembled as two layers of hexameric rings associated face to face (Eisenberg et al., 2000; Stadtman and Ginsburg, 1974). Eukaryotic synthetases, designated GS II, are less understood, but essential aspects of their reaction mechanisms appear to be similar to that of GS I (Eisenberg et al., 2000; Meister, 1974a). Both GS I and GS II can be found in bacteria, although GS I is predominant. Eukaryotes contain only GS II. In this chapter, we discuss the reaction mechanism of GS I and GS II and the structure of GS I.

The standard gibbs free energy change of hydrolysis of α-d-ribose 1-phosphate

1980 ◽  
Vol 205 (1) ◽  
pp. 191-197 ◽  
Author(s):  
Marcella Camici ◽  
Francesco Sgarrella ◽  
Pier L. Ipata ◽  
Umberto Mura
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Free Energy Change ◽  
Energy Change ◽  
Standard Gibbs Free Energy ◽  
Gibbs Free Energy Change ◽  
Hydrolysis Of

The enol content of simple carbonyl compounds: a thermochemical approach

1979 ◽  
Vol 57 (2) ◽  
pp. 240-248 ◽  
Author(s):  
J. Peter Guthrie ◽  
Patricia A. Cullimore
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Carbonyl Compounds ◽  
Free Energy Change ◽  
Energy Change ◽  
Free Energies ◽  
Enol Ethers ◽  
Free Energy Of Formation ◽  
Hydrolysis Of ◽  
Energy Of Formation

From the heats of hydrolysis of enol ethers, the heats of formation of the enol ethers, and thence the free energies of formation of the enol ethers in aqueous solution can be calculated. For this calculation it was necessary to determine the free energies of transfer from the gas phase to aqueous solution. By methods previously published it was possible to estimate the free energy change for the hypothetical hydrolysis reaction leading from the enol ether to the enol, which in turn made possible calculation of the free energy of formation of the enol. Finally the free energy change for enolization in aqueous solution could be calculated using the known free energy of formation of the corresponding keto tautomer. In this way the following were determined: carbonyl compound, pKenol = −log ([enol]/[keto]): acetaldehyde, 5.3; propionaldehyde, 3.9; isobutyraldehyde, 2.8; acetone, 7.2; 2-butanone, 8.3; 3-pentanone, 7.8; cyclopentanone, 7.2; cyclohexanone, 5.7; acetophenone, 6.7.

The Enzymic Hydrolysis of Acetyl-Coenzyme A by Trypanosomatid Flagellates

1976 ◽  
Vol 4 (2) ◽  
pp. 285-287 ◽  
Author(s):  
ROGER A. KLEIN ◽  
PETER G. G. MILLER ◽  
DAVID J. LINSTEAD
Keyword(s):  
Coenzyme A ◽  
Enzymic Hydrolysis ◽  
Acetyl Coenzyme A ◽  
Acetyl Coenzyme ◽  
Hydrolysis Of
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