Steady-State Kinetic Isotope Effects Support a Complex Role of Arg226 in the Proposed Desulfonation Mechanism of Alkanesulfonate Monooxygenase

Biochemistry ◽  
2013 ◽  
Vol 53 (1) ◽  
pp. 161-168 ◽  
Author(s):  
John M. Robbins ◽  
Holly R. Ellis
Keyword(s):  
Steady State ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Kinetic Isotope ◽  
Steady State Kinetic ◽  
Alkanesulfonate Monooxygenase ◽  
State Kinetic

scholarly journals The mechanism of action of β-galactosidase. Effect of aglycone nature and α-deuterium substitution on the hydrolysis of aryl galactosides

1973 ◽  
Vol 133 (1) ◽  
pp. 89-98 ◽  
Author(s):  
Michael L. Sinnott ◽  
Ian J. L. Souchard
Keyword(s):  
Steady State ◽  
Isotope Effects ◽  
Ion Pair ◽  
Enzyme Mechanism ◽  
Kinetic Isotope ◽  
Deuterium Substitution ◽  
Steady State Kinetic ◽  
Hydrolysis Of ◽  
State Kinetic ◽  
Step Mechanism

1. Steady-state kinetic parameters for the β-galactosidase-catalysed hydrolysis of 13 aryl β-d-galactopyranosides show no simple dependence on aglycone acidity. 2. α-Deuterium kinetic isotope effects (kH/kD) for seven of these substrates, measured under steady-state conditions with [S]»Km, vary from 1.00 for poor substrates to 1.25 for hydrolysis of the galactosyl-enzyme. 3. Methanolysis of the galactosyl-enzyme in 1.5m-methanol increases KH/kD for degalactosylation, but leaves that for hydrolysis of ‘slow’ substrates unchanged. 4. These data are incompatible with a simple two-step mechanism. A scheme consisting of a conformation change, liberation of a galactopyranosyl cation in an intimate ion-pair, non-productive but preferential collapse of the ion-pair to a covalent species and reaction of the galactosyl enzyme through the ion-paired form is proposed. 5. This scheme is used to rationalize previously puzzling data about the enzyme mechanism.

Interpretation of Transient-State Kinetic Isotope Effects†

Biochemistry ◽  
1996 ◽  
Vol 35 (1) ◽  
pp. 83-88 ◽  
Author(s):  
Harvey F. Fisher ◽  
Swapan K. Saha
Keyword(s):  
Isotope Effects ◽  
Transient State ◽  
Kinetic Isotope Effects ◽  
Kinetic Isotope ◽  
State Kinetic

scholarly journals Role of Microsolvation and Quantum Effects in the Accurate Prediction of Kinetic Isotope Effects: The Case of Hydrogen Atom Abstraction in Ethanol by Atomic Hydrogen in Aqueous Solution

2020 ◽  
Vol 16 (2) ◽  
pp. 847-859 ◽  
Author(s):  
Suraj Kannath ◽  
Paweł Adamczyk ◽  
David Ferro-Costas ◽  
Antonio Fernández-Ramos ◽  
Dan Thomas Major ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Atom ◽  
Atomic Hydrogen ◽  
Isotope Effects ◽  
Quantum Effects ◽  
Kinetic Isotope Effects ◽  
Accurate Prediction ◽  
Hydrogen Atom Abstraction ◽  
Kinetic Isotope

Secondary Kinetic Isotope Effects in Bimolecular Nucleophilic Substitutions. V. The Role of the Solvent in the Reaction Between Methyl Iodide and Pyridine

1972 ◽  
Vol 50 (7) ◽  
pp. 982-985 ◽  
Author(s):  
K. T. Leffek ◽  
A. F. Matheson
Keyword(s):  
Transition State ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
State Structure ◽  
Transition State Structure ◽  
Initial State ◽  
Nucleophilic Substitutions ◽  
Kinetic Isotope ◽  
Deuterium Isotope Effects

Secondary kinetic deuterium isotope effects are presented for the reaction of methyl-d3 iodide and pyridine in four different solvents. Calculations on mass and moment of inertia change with deuteration in the initial state and an assumed tetrahedral transition state, together with internal rotational effects, are used to rationalize the inverse isotope effects. It is concluded from the variation of the isotopic rate ratio, that the transition state structure varies with solvent.

On the application of the steady state to kinetic isotope effects

1985 ◽  
Vol 107 (24) ◽  
pp. 7070-7071 ◽  
Author(s):  
Piotr Paneth
Keyword(s):  
Steady State ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Kinetic Isotope

scholarly journals Kinetic Isotope Effects for Alkaline Phosphatase Reactions:  Implications for the Role of Active-Site Metal Ions in Catalysis

2007 ◽  
Vol 129 (31) ◽  
pp. 9789-9798 ◽  
Author(s):  
Jesse G. Zalatan ◽  
Irina Catrina ◽  
Rebecca Mitchell ◽  
Piotr K. Grzyska ◽  
Patrick J. O'Brien ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Metal Ions ◽  
Active Site ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Kinetic Isotope
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