KINETICS OF THE INHIBITION OF α-CHYMOTRYPSIN BY METHANOL AND DFP

1959 ◽  
Vol 37 (8) ◽  
pp. 1272-1277 ◽  
Author(s):  
Bernard R. Stein ◽  
Keith J. Laidler
Keyword(s):  
Aqueous Solution ◽  
Substrate Concentration ◽  
Pure Water ◽  
Inhibition Constant ◽  
Specific Mechanism ◽  
Ph Optimum ◽  
Diisopropyl Phosphorofluoridate ◽  
No Inhibition ◽  
Kinetics Of ◽  
Hydrolysis Of

A study has been made of the kinetics of the α-chymotrypsin-catalyzed hydrolysis of methyl hydrocinnamate in the presence of various concentrations of methanol, of eserine, and of diisopropyl phosphorofluoridate (DFP). In 20% methanol the pH optimum, using a substrate concentration of 1.20 × 10−3M, is 7.8; in pure water it is 8.3; and at intermediate pH's the optimum varies between these values. No inhibition was observed with eserine. In aqueous solution the character of the inhibition by DFP differs from that in alcohol solutions; the inhibition is of the competitive type, and the inhibition constant varies with pH in essentially the same manner as does the rate of the reaction. This result suggests that DFP interacts with the same active groups on the enzyme as are responsible for the hydrolysis of the substrate. A specific mechanism for inhibition is suggested.

Early stages of the hydrolysis of chromium(III) in aqueous solution—VII. Kinetics of dimerization of deprotonated forms of doubly bridged dimer

Polyhedron ◽  
1991 ◽  
Vol 10 (20-21) ◽  
pp. 2389-2397 ◽  
Author(s):  
Michael R. Grace ◽  
Leone Spiccia
Keyword(s):  
Aqueous Solution ◽  
Early Stages ◽  
Kinetics Of ◽  
Hydrolysis Of

Early stages of the hydrolysis of chromium(III) in aqueous solution. 3. Kinetics of dimerization of the deprotonated aqua ion

1986 ◽  
Vol 25 (4) ◽  
pp. 489-495 ◽  
Author(s):  
Francois P. Rotzinger ◽  
Hans Stuenzi ◽  
Werner Marty
Keyword(s):  
Aqueous Solution ◽  
Early Stages ◽  
Kinetics Of ◽  
Hydrolysis Of

Reactivity of base catalysed hydrolysis of 2-pyridinylmethylene-8-quinolinyl-Schiff base iron(II) iodide complexes: solvent effects

2013 ◽  
Vol 67 (4) ◽  
Author(s):  
Ahmad Mohamad ◽  
Mohamed Adam
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Solvent Effects ◽  
Base Hydrolysis ◽  
Iodide Ions ◽  
Ligand Structure ◽  
Solvation Parameters ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Direct Condensation

AbstractThree ligands of 2-pyridinylmethylene-8-quinolinyl (L1), methyl-2-pyridinylmethylene-8-quinolinyl (L2), and phenyl-2-pyridinylmethylene-8-quinolinyl (L3), Schiff bases were synthesised by direct condensation of 8-aminoquinoline with 2-pyridinecarboxaldehyde, 2-acetylpyridine, or 2-benzoylpyridine. They coordinated to Fe(II) ion in a 1: 2 mole ratio followed by treatment with iodide ions affording complexes with a general formula [Fe(L)2]I2·2H2O, (L = L1, L2, or L3). Spectrophotometric evaluation of the kinetics of base catalysed hydrolysis of these complex cations was carried out with an aqueous solution of NaOH in different ratios of water/methanol binary mixtures. Kinetics of the hydrolysis followed the rate law (k 2[OH−] + k 3[OH−]2)[complex]. Reactivity trends and their rate constants were compared and discussed in terms of ligand structure and solvation parameters. The methanol ratio affects the hydrolysis as a co-solvent which was analysed into initial and transition state components. The increase in the rate constant of the base hydrolysis of Fe(II) complexes, as the ratio of methanol increases, is predominantly caused by the strong effect of the organic co-solvent on the transition states.

The acid-catalysed hydrolysis of α-methylallyl acetate in aqueous solution

1968 ◽  
Vol 21 (7) ◽  
pp. 1727
Author(s):  
RA Fredlein ◽  
I Lauder
Keyword(s):  
Aqueous Solution ◽  
Reaction Products ◽  
Arrhenius Parameters ◽  
Crotyl Alcohol ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Tracer Experiments

The kinetics of the acid-catalysed hydrolysis of a-methylallyl acetate in aqueous solution have been studied over the range 30-100�. Oxygen-18 tracer experiments reveal the mechanism to be solely Aac2 and the Arrhenius parameters are consistent with this conclusion. Crotyl alcohol is observed in the reaction products. The formation of rearranged alcohol is explained by allylic isomerization of the α-methylallyl alcohol produced by the hydrolysis.

Kinetics of the hydrolysis of acyl chlorides in pure water

1967 ◽  
Vol 45 (14) ◽  
pp. 1619-1629 ◽  
Author(s):  
A. Queen
Keyword(s):  
Pure Water ◽  
Activation Parameters ◽  
Acyl Chlorides ◽  
Reversible Addition ◽  
Electron Donation ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Chlorine Bond ◽  
Oxygen Bond ◽  
Bimolecular Mechanism

The activation parameters ΔH≠, ΔS≠, and ΔCP≠ for the hydrolyses of a series of alkyl chloroformates and dimethylcarbamyl chloride in water have been determined. The results indicate that, with increasing electron donation to the chlorocarbonyl group, the mechanism changes from bimolecular to unimolecular (SN1) displacement at this position. For isopropyl chloroformate, some concurrent alkyl–oxygen bond fission is also indicated. The bimolecular mechanism involves reversible addition of water to the carbonyl group followed by ionization of the carbon–chlorine bond.

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