Studies on Chymotrypsin-P. II. Kinetics

1972 ◽  
Vol 50 (7) ◽  
pp. 846-847 ◽  
Author(s):  
M. C. Shaw ◽  
T. Viswanatha
Keyword(s):  
Ethyl Ester ◽  
Catalytic Properties ◽  
Feature Characteristic ◽  
Catalyzed Reactions ◽  
A Chain ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Chymotrypsin A

A comparison of the kinetics of chymotrypsin-P catalyzed hydrolysis of N-acetyl-L-tyrosine ethyl ester and cinnamoylimidazole with those of the chymotrypsin Aα catalyzed reactions revealed the two enzymes to possess very similar catalytic properties. The deletion of the three C-terminal residues from the A-chain of chymotrypsin Aα, a feature characteristic of chymotrypsin-P, does not lead to significant changes in the function of the enzyme.

Steady-State Kinetics of Enzyme Reactions in the Presence of Added Nucleophiles

1972 ◽  
Vol 50 (12) ◽  
pp. 1334-1359 ◽  
Author(s):  
Irwin Hinberg ◽  
Keith J. Laidler
Keyword(s):  
Specific Binding ◽  
Specific Binding Sites ◽  
Steady State Kinetics ◽  
Special Cases ◽  
Kinetics Of Formation ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions ◽  
Concentration Graphs ◽  
Kinetics Of ◽  
Hydrolysis Of

Many enzyme-catalyzed reactions, such as hydrolyses, give rise to two products P1 and P2 which are formed in different reaction steps. The second product P2 is frequently formed by hydrolysis of an intermediate such as an acyl-enzyme or a phosphoryl-enzyme. An alternative nucleophile N introduced into the system forms an additional product P3. The present paper is concerned with the kinetics of formation of P1, P2, and P3 in the presence of added nucleophiles. A number of alternative mechanisms are considered, and equations are derived for the rates of formation of the three products, and the Michaelis constant, as functions of nucleophile concentration. Graphs are presented showing the variations of these parameters with the concentration of N, for a variety of special cases. Special attention is given to the possibility of specific binding sites for the water and the nucleophile molecules.The data for a number of enzyme systems are discussed with reference to the treatment. For reactions catalyzed by alkaline phosphatase it is concluded that only one mechanism (mechanism VI) is consistent with the results.

Metal complex catalyzed reactions of anils. III. Kinetic and mechanistic studies

1977 ◽  
Vol 55 (12) ◽  
pp. 2432-2441 ◽  
Author(s):  
A. R. Boate ◽  
D. R. Eaton
Keyword(s):  
Aqueous Solution ◽  
Metal Complex ◽  
Metal Atom ◽  
Nucleophilic Attack ◽  
Mechanistic Studies ◽  
Acetone Molecule ◽  
Rate Determining Step ◽  
Catalyzed Reactions ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of the homogeneously catalyzed formation and hydrolysis of anils in non-aqueous solution have been studied. The catalysts used are zinc complexes of thiourea. It is shown that all the evidence obtained, kinetic and otherwise, is consistent with a model in which the rate determining step for anil formation is nucleophilic attack by an aniline held in the second coordination sphere of the metal complex on an acetone molecule directly bound to the metal atom. Analogous mechanisms are suggested for anil hydrolysis and for transimination.

Kinetics of α-chymotrypsin action. III. Mechanisms of inhibition

1967 ◽  
Vol 45 (5) ◽  
pp. 559-565 ◽  
Author(s):  
Harvey Kaplan ◽  
Keith J. Laidler
Keyword(s):  
Experimental Study ◽  
Ethyl Ester ◽  
Free Enzyme ◽  
General Mechanism ◽  
Competitive Behavior ◽  
Mechanism Of Inhibition ◽  
Quantitative Manner ◽  
Order Sequence ◽  
Kinetics Of ◽  
Hydrolysis Of

An experimental study was made of the α-chymotrypsin-catalyzed hydrolysis of N-acetyl-l-tyrosine ethyl ester, inhibited by indole and phenol. Indole inhibits noncompetitively, and analysis of the behavior shows that it binds to the enzyme and the acyl enzyme but not to the Michaelis complex; by binding to the acyl enzyme, it blocks deacylation. Phenol exhibits competitive behavior, two molecules of phenol being bound to the free enzyme in a forced-order sequence. It is concluded from the kinetics that there is either no binding of phenol to the acyl enzyme, or binding which does not affect the rate of deacylation. A general mechanism of inhibition is shown, to explain in a quantitative manner these and other inhibition results.

The effect of ethanol on the kinetics of lipase-mediated enantioselective esterification of 4-methyloctanoic acid and the hydrolysis of its ethyl ester

2001 ◽  
Vol 76 (3) ◽  
pp. 193-199 ◽  
Author(s):  
Nicole W. J. T. Heinsman ◽  
Ana M. Valente ◽  
Henry G. F. Smienk ◽  
Albert van der Padt ◽  
Maurice C. R. Franssen ◽  
...  
Keyword(s):  
Ethyl Ester ◽  
Kinetics Of ◽  
Hydrolysis Of

Influence of Anionic Surfactants and Ionic Strength on α-Coymotrypsin-Catalyzed Reactions

1972 ◽  
Vol 50 (4) ◽  
pp. 392-398 ◽  
Author(s):  
J. E. Gaudin ◽  
T. Viswanatha
Keyword(s):  
Ionic Strength ◽  
Sodium Dodecyl Sulfate ◽  
Ethyl Ester ◽  
Sodium Dodecyl ◽  
Reaction Medium ◽  
Protein Ratio ◽  
Low Concentrations ◽  
Dodecyl Sulfate ◽  
Catalyzed Reactions ◽  
Hydrolysis Of

The effect of sodium dodecyl sulfate and sodium decylbenzene sulfonate on the chymotrypsin-catalyzed hydrolysis of N-acetyl-L-tyrosine ethyl ester was investigated. Pretreatment of the enzyme with sodium dodecyl sulfate produces inactivation which is dependent on the ratio of the surfactant to protein. Total loss of activity is achieved at a surfactant to protein (w/w) ratio of 15. Addition of chymotrypsin to a mixture of detergent and substrate does not affect the activity of the enzyme at low concentrations of sodium dodecyl sulfate. An enhancement in the activity is noted at higher surfactant concentrations, presumably due to the increase in the ionic strength of the reaction medium. The reaction of sodium decylbenzene sulfonate with chymotrypsin results in the formation of a series of complexes in an 'all or none' manner. Inactivation of the enzyme is noted initially at a surfactant to protein ratio of 1.0 and subsequently at ratios higher than 10. However, considerable activity is retained at surfactant to protein ratios of 3:5. The hydrolysis of N-acetyl-L-tyrosine ethyl ester is considerably influenced by the ionic strength of the medium. Increases in the ionic strength cause an enhancement in Vmax without affecting the affinity of the enzyme for the substrate.

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