Thermodynamics of fatty acid degradation.

In this communication, the correlation of some thermodynamic properties of structurally similar biological compounds with items such as the number of carbon atoms or the number of its characteristic groups, such as phosphates, was applied to enzyme thermodynamics, to advance the thermodynamics of fatty acid degradation. It was shown that these concepts apply equally well for all three major thermodynamic functions: Gibbs energy of formation, enthalpy of formation, and entropy of formation. First, the standard transformed Gibbs energies of formation, Δ(f)G'(o), were calculated for the major portion of saturated fatty acids at 25 °C and pH 5, pH 7, and pH 9.

Deriving the rate equations for product inhibition patterns in bisubstrate enzyme reactions.

In this work, the full rate equations for 17 completely reversible bisubstrate enzyme kinetic mechanisms, with two substrates in the forward and two in the reverse direction, have been presented; among these are rapid equilibrium, steady-state, and mixed steady-state and rapid equilibrium mechanisms. From each rate equation eight product inhibition equations were derived, four for the forward and four for the reverse direction. All the corresponding product inhibition equations were derived in full; thus a total of 17 x 8 = 136 equations, were presented.

Glucose oxidase from Aspergillus niger: the mechanism of action with molecular oxygen, quinones, and one-electron acceptors.

Glucose oxidase from the mold Aspergillus niger (EC 1.1.3.

Inactivation of cytochrome-c with glucose oxidase.

A novel reaction of cytochrome-c from the horse heart with the enzyme glucose oxidase from Aspergillus niger (EC 1.1.3.

The chemical mechanism of action of glucose oxidase from Aspergillus niger.

Glucose oxidase from Aspergillus niger (EC 1.1.3.

A general method for the analysis of random bisubstrate enzyme mechanisms.

In the present communication, a general method for the kinetic analysis of random bisubstrate mechanisms is described. The method comprises a stepwise application of the following kinetic and ligand-binding experiments: determination of steady-state kinetic constants, product inhibition patterns, maximum rate relationships, application of alternate substrates, application of dead-end inhibitors, direct binding of substrates, kinetic isotope effects, and isotope exchange studies. This general method was applied to a practical example: a yeast alcohol dehydrogenase-catalyzed oxidation of 2-propanol by NAD(+) at pH 7.

The three zinc-containing alcohol dehydrogenases from baker's yeast, Saccharomyces cerevisiae.

This review is a summary of our current knowledge of the structure, function and mechanism of action of the three zinc-containing alcohol dehydrogenases, YADH-1, YADH-2 and YADH-3, in baker's yeast, Saccharomyces cerevisiae. The opening section deals with the substrate specificity of the enzymes, covering the steady-state kinetic data for its most known substrates. In the following sections, the kinetic mechanism for this enzyme is reported, along with the values of all rate constants in the mechanism.

Bioorganic mechanisms of the formation of free radicals catalyzed by glucose oxidase.

In this communication, we have described the activation of several xenobiotics by glucose oxidase from Aspergillus niger. The following compounds are readily reduced by d-glucose, in the presence of glucose oxidase: p-nitroso-N,N-dimethylaniline, methyl-1,4-benzoquinone, and 7,7,8,8-tetracyano-quinodimethane. In each case, the products of enzymatic reduction undergo a dismutation reaction with the parent compound and thus afford the formation of free radicals.

Comparison of the chemical mechanisms of action of yeast and equine liver alcohol dehydrogenase.

The pH-dependence of the steady-state kinetic parameters and the ligand-binding parameters for competitive dead-end inhibitors for the yeast alcohol dehydrogenase (EC 1.1.1.

Novel substrates of yeast alcohol dehydrogenase--4. Allyl alcohol and ethylene glycol.

In the present work, we have determined the steady-state kinetic constants for yeast alcohol dehydrogenase-catalyzed oxidation of allyl alcohol (H2C = CH.CH2OH) and ethylene glycol (HOCH2.CH2OH) with NAD+, at pH 8.

Influence of Tris(hydroxymethyl)aminomethane on kinetic mechanism of yeast alcohol dehydrogenase.

Acetaldehyde, propionaldehyde, glyceraldehyde-3-P and 4-dimethylaminocinnamaldehyde form Schiff bases in Tris. HCl buffers; the rates of formation and dissociation of Schiff bases, and equilibrium constants for their formation are very similar for the first three aldehydes. The steady-state kinetic constants for the yeast alcohol dehydrogenase-catalyzed reaction, propan-1-ol + NAD+ reversible propionaldehyde + NADH + H+, have been determined in several Tris.

Use of competitive dead-end inhibitors to determine the chemical mechanism of action of yeast alcohol dehydrogenase.

In this work, we have postulated a comprehensive and unified chemical mechanism of action for yeast alcohol dehydrogenase (EC 1.1.1.

Novel substrates of yeast alcohol dehydrogenase-3. 4-dimethylamino-cinnamaldehyde and chloroacetaldehyde.

4-Dimethylamino-trans-cinnamaldehyde and chloroacetaldehyde are novel substrates of yeast alcohol dehydrogenase (EC 1.1.1.

Simple and rapid chromatographic method for the separation of major classes of ribosomal ribomononucleotides.

We have described a simple and rapid chromatographic method for the analytical and preparative separation of major types of ribosomal ribomononucleotides with Dowex 1-X10 (HCOO-, 37-74 microns) and Dowex 2-X10 (HCOO-, 37-74 microns) columns, by desorption with formiate solutions in 1-2 h. The separation has been achieved for Cp, Ap, Up and Gp, while a mixture of 2'-, and 3'-nucleoside phosphates desorbs as a single peak; with both resins, a successful separation was achieved with a load from 25 micrograms to 1 mg of ribomononucleotide mixture per ml of packed resin. A complete separation was achieved with Dowex 1, while the separation with Dowex 2 resin was even better.

Use of pH studies to determine the kinetic and chemical mechanism of yeast alcohol dehydrogenase with primary aliphatic alcohols and aldehydes.

A complete list of all steady-state kinetic constants for the yeast alcohol dehydrogenase (EC 1.1.1.

Yeast alcohol dehydrogenase catalyzed reduction of p-nitroso-N, N-dimethylaniline by NADH.

The steady-state kinetics, product identification, stoichiometries, and solvent isotope effects of yeast alcohol dehydrogenase catalyzed reduction of p-nitroso-N,N-dimethylaniline (NDMA) by NADH, are reported. NDMA is enzymatically reduced to p-hydroxylamine-N,N-dimethylaniline, which is further enzymatically dehydrated to corresponding quinonediimine cation (QDI+). QDI+ undergoes nonenzymatic transformations.

Primary toxic effects of anthraquinone-2-sulfonic acid in rat liver microsomes.

(1) The endogenous, NADPH-supported production of H2O2 and of O2-.-radicals in rat liver microsomes was very strongly enhanced in the presence of anthraquinone-2-sulfonic acid (AQSA). (2) This induction of H2O2 and of O2-.

A novel spectrophotometric method for the enzymatic determination of NAD+ and NADH.

The theory and practice of a novel spectrophotometric method for the enzymatic determination of NAD+ and NADH is described. The method can not discriminate between NAD+ and NADH, but determines the concentration of the sum of both nucleotides. The method is based on the bleaching of p-nitroso-N,N-dimethylaniline (NMDA) (epsilon 440 nm = 35400 M-1cm-1) with NADH, in the presence of ethanol and yeast alcohol dehydrogenase, under the conditions of enzymatic cycling (ethanol > NDNA > NAD/H).

Kinetic mechanism of yeast alcohol dehydrogenase activity with secondary alcohols and ketones.

The kinetic mechanism of yeast alcohol dehydrogenase (EC 1.1.1.

Kinetic mechanism of yeast alcohol dehydrogenase with primary aliphatic alcohols and aldehydes.

Yeast alcohol dehydrogenase (EC 1.1.1.

A simple fluorimetric method for the estimation of ligand binding parameters in ligand-enzyme complexes.

The theory and practice of a simple fluorimetric method for the estimation of ligand binding parameters in ligand-enzyme complexes is described. In this method, the concentration of a ligand-binding enzyme and the dissociation constant of a ligand-enzyme complex were estimated solely from the total concentration of a ligand and the total fluorescence of the ligand in the absence and in the presence of enzyme.

Reduction of 1-nitroso-2-naphthol by NADPH in the presence of liver microsomes.

1. The endogenous, NADPH-supported production of H2O2 and of O2-.-radicals in liver microsomes, was very strongly enhanced in the presence of 1-nitroso-2-naphthol.

Hepatic metabolism of artemisinin drugs--III. Induction of hydrogen peroxide production in rat liver microsomes by artemisinin drugs.

1. In this communication, induction of hydrogen peroxide production by the semisynthetic antimalarial drugs of the artemisinin class (beta-arteether, beta-artelinic acid and dihydroartemisinin) in rat liver microsomes, is reported. 2.

Redox-elimination reaction catalyzed by yeast alcohol dehydrogenase.

Yeast alcohol dehydrogenase (EC 1.1.1.

Hepatic metabolism of artemisinin drugs--II. Metabolism of arteether in rat liver cytosol.

1. In this communication, in vitro metabolism of a semisynthetic antimalarial drug arteether in rat liver cytosol is reported. 2.