A SIMPLIFIED APPROACH TO THE USE OF DETERMINANTS IN THE CALCULATION OF THE RATE EQUATION FOR A COMPLEX ENZYME SYSTEM

1967 ◽  
Vol 45 (12) ◽  
pp. 2015-2039 ◽  
Author(s):  
R. O. Hurst
Keyword(s):  
Reaction Mechanism ◽  
Rate Equation ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Enzyme System ◽  
Inhibition Mechanism ◽  
Simplified Approach ◽  
Enzymic Reaction ◽  
Dead End ◽  
Search For Information

A standardized method of treating the analysis of enzymic reaction mechanisms by means of determinant expressions is given. The fully expanded polynomial expressions for systems of order three, four, and five are presented and their use described. Application of the method to the analysis of the effect of dead-end inhibitors on enzymic reactions is discussed and the inhibitor constants are evaluated in terms of the rate constants involved in the inhibition mechanism. Examples are given to demonstrate the contribution that inhibitor studies may make in the search for information concerning the nature of the enzymic reaction mechanism, in the calculation of the rate constants, and in the estimation of the proportion of the enzyme distributed between the different enzyme forms involved in the reaction.

The analysis of dead-end inhibition patterns for multisubstrate systems

1969 ◽  
Vol 47 (2) ◽  
pp. 91-108
Author(s):  
R. O. Hurst
Keyword(s):  
Reaction Mechanism ◽  
Rate Equation ◽  
Rate Constants ◽  
Additive Effect ◽  
Enzyme Form ◽  
Linear Fashion ◽  
Dead End ◽  
Ping Pong ◽  
Full Rate ◽  
Enzyme Species

The additive effect of a dead-end inhibitor combining in linear fashion with more than one of the enzyme species in a reaction mechanism is demonstrated. An equation for the calculation of the inhibitor constants that are required for the multicombinations of inhibitor from those obtained for the inhibitor combining with only one enzyme form is provided. A method of tabulation of the inhibitor constants with respect to the coefficients of the denominator terms of the full rate-equation for the uninhibited reaction is given, that facilitates the analysis of the inhibition patterns for the several inhibitor complexes that may be formed. The usefulness of the method for calculating the rate constants for a 'Ping Pong Bi Bi' mechanism is illustrated.

scholarly journals Temperature response of Rubisco kinetics in Arabidopsis thaliana: thermal breakpoints and implications for reaction mechanisms

2018 ◽  
Author(s):  
Ryan A. Boyd ◽  
Amanda P. Cavanagh ◽  
David S. Kubien ◽  
Asaph B. Cousins
Keyword(s):  
Arabidopsis Thaliana ◽  
Reaction Mechanism ◽  
Kinetic Parameters ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Temperature Response ◽  
Concentration Changes ◽  
The Individual ◽  
Temperature Responses ◽  
Individual Rate

ABSTRACTOptimization of Rubisco kinetics could improve photosynthetic efficiency, ultimatly resulting in increased crop yield. However, imprecise knowledge of the reaction mechanism and the individual rate constants limit our ability to optimize the enzyme. Membrane inlet mass spectrometery (MIMS) may offer benefits over traditional methods for determining individual rate constants of the Rubisco reaction mechanism, as it can directly monitor concentration changes in CO2, O2, and their isotopologs during assays. However, a direct comparsion of MIMS to the traditional Radiolabel method of determining Rubisco kinetic parameters has not been made. Here, the temperature responses of Rubisco kinetic parameters from Arabidopsis thaliana were measured using the Radiolabel and MIMS methods. The two methods provided comparable parameters above 25 °C, but temperature responses deviated at low temperature as MIMS derived catalytic rates of carboxylation, oxygenation, and CO2/O2 specificity showed thermal breakpoints. Here we discuss the variability and uncertainty surrounding breakpoints in the Rubisco temperature response and relavance of individual rate constants of the reaction mechanisms to potential breakpoints.

Mutarotation of D(+)-glucose. II. Volumes of activation for the uncatalysed and copper(II)-catalysed rates

1983 ◽  
Vol 36 (2) ◽  
pp. 279 ◽  
Author(s):  
CJ O'Conner ◽  
AL Odell ◽  
AAT Bailey
Keyword(s):  
High Pressure ◽  
Reaction Mechanism ◽  
Equilibrium Constant ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Sodium Perchlorate ◽  
Continuous Series ◽  
Aqueous Sodium ◽  
The Individual ◽  
Individual Rate

The effect of high pressure on the rate of mutarotation of α-and β-D(+)-glucose in aqueous sodium perchlorate solutions has been evaluated. The observed rate constant kΨ = kα + kβ increases with pressure while the equilibrium constant Keq = kα /kβ is nearly unchanged from the 1.7 found at 1 bar. From the experimental results, the individual rate constants kα and kβ and the corresponding activation volumes ∆V‡α and ∆V‡β can be evaluated. The values obtained, -10.7 � 0.1 and -10.0 � 0.1 cm3 mol-1, are discussed in relation to the reaction mechanism. In the presence of Cu(ClO4)2 the values of ∆V: form a continuous series, dependent upon the pH and the concentration of copper(II) catalyst, up to + 1.3 cm3 mol-1. The activation volumes for mutarotation by monomeric and dimeric copper(II) catalysts, ∆V‡(Cu2+) and ∆V‡ {CU((OH)2Cu)2+}, are -1.2 � 0.2 and + 3.6 � 0.2 cm3 mol-1 respectively. Reaction mechanisms are discussed to account for these values of ∆V‡.

Alternative mechanism for a bimolecular nonsequential enzymic reaction

1969 ◽  
Vol 47 (2) ◽  
pp. 111-115 ◽  
Author(s):  
R. O. Hurst
Keyword(s):  
Reaction Mechanism ◽  
Product Inhibition ◽  
Alternative Mechanism ◽  
Enzymic Reaction ◽  
Dead End ◽  
Ping Pong ◽  
Inhibition Studies ◽  
Different Order ◽  
Inhibition Pattern

An enzymic reaction mechanism characterized as 'di-Uni Iso Ping Pong' which has the same product inhibition pattern as the 'Ping Pong Bi Bi' mechanism but a different order for the release of products is discussed. A basis for differentiating the two mechanisms by dead-end inhibition studies is given.

scholarly journals A kinetic study of baker's-yeast pyruvate kinase activated by fructose 1,6-diphosphate

1972 ◽  
Vol 129 (5) ◽  
pp. 1035-1047 ◽  
Author(s):  
Neil Macfarlane ◽  
Stanley Ainsworth
Keyword(s):  
Reaction Mechanism ◽  
Kinetic Study ◽  
Pyruvate Kinase ◽  
Rate Constants ◽  
Experimental Results ◽  
Phosphoryl Transfer ◽  
Dead End ◽  
Inhibition Constants ◽  
Quaternary Complex ◽  
Kinetics Of

The paper reports a study of the kinetics of the reaction between phosphoenolpyruvate, ADP and Mg2+catalysed by yeast pyruvate kinase when activated by fructose 1,6-diphosphate and K+. The experimental results indicate that the reaction mechanism is of the Ordered Tri Bi type with the substrates binding in the order phosphoenolpyruvate, ADP and Mg2+. Direct phosphoryl transfer takes place in the quaternary complex, with pyruvate released before MgATP. A dead-end enzyme–pyruvate complex is also indicated. Values have been determined for the Michaelis, dissociation and inhibition constants of the reaction. Several of the rate constants involved have also been evaluated.

A Paramedic Treatment for Modeling Explicitly Solvated Chemical Reaction Mechanisms

2018 ◽  
Author(s):  
Yasemin Basdogan ◽  
John Keith
Keyword(s):  
Reaction Mechanism ◽  
Chemical Reaction ◽  
Reaction Mechanisms ◽  
Reaction Pathway ◽  
Optimization Procedure ◽  
Cost Effective ◽  
Chemical Reaction Mechanisms ◽  
Solvent Molecules ◽  
Dynamics Simulations ◽  
Mbh Reaction

<div> <div> <div> <p>We report a static quantum chemistry modeling treatment to study how solvent molecules affect chemical reaction mechanisms without dynamics simulations. This modeling scheme uses a global optimization procedure to identify low energy intermediate states with different numbers of explicit solvent molecules and then the growing string method to locate sequential transition states along a reaction pathway. Testing this approach on the acid-catalyzed Morita-Baylis-Hillman (MBH) reaction in methanol, we found a reaction mechanism that is consistent with both recent experiments and computationally intensive dynamics simulations with explicit solvation. In doing so, we explain unphysical pitfalls that obfuscate computational modeling that uses microsolvated reaction intermediates. This new paramedic approach can promisingly capture essential physical chemistry of the complicated and multistep MBH reaction mechanism, and the energy profiles found with this model appear reasonably insensitive to the level of theory used for energy calculations. Thus, it should be a useful and computationally cost-effective approach for modeling solvent mediated reaction mechanisms when dynamics simulations are not possible. </p> </div> </div> </div>

Determination of Complex Reaction Mechanisms

2006 ◽  
Author(s):  
John Ross ◽  
Igor Schreiber ◽  
Marcel O. Vlad
Keyword(s):  
Reaction Mechanism ◽  
Reaction Mechanisms ◽  
Reaction Pathway ◽  
Chemical Species ◽  
Rate Coefficients ◽  
Chemical System ◽  
Evolutionary Development ◽  
Complex Reaction ◽  
Oscillatory Reactions

In a chemical system with many chemical species several questions can be asked: what species react with other species: in what temporal order: and with what results? These questions have been asked for over one hundred years about simple and complex chemical systems, and the answers constitute the macroscopic reaction mechanism. In Determination of Complex Reaction Mechanisms authors John Ross, Igor Schreiber, and Marcel Vlad present several systematic approaches for obtaining information on the causal connectivity of chemical species, on correlations of chemical species, on the reaction pathway, and on the reaction mechanism. Basic pulse theory is demonstrated and tested in an experiment on glycolysis. In a second approach, measurements on time series of concentrations are used to construct correlation functions and a theory is developed which shows that from these functions information may be inferred on the reaction pathway, the reaction mechanism, and the centers of control in that mechanism. A third approach is based on application of genetic algorithm methods to the study of the evolutionary development of a reaction mechanism, to the attainment given goals in a mechanism, and to the determination of a reaction mechanism and rate coefficients by comparison with experiment. Responses of non-linear systems to pulses or other perturbations are analyzed, and mechanisms of oscillatory reactions are presented in detail. The concluding chapters give an introduction to bioinformatics and statistical methods for determining reaction mechanisms.

scholarly journals Reaction Mechanisms and Rate Constants of Auto‐Catalytic Urethane Formation and Cleavage Reactions

ChemistryOpen ◽  
2021 ◽  
Author(s):  
Christoph Gertig ◽  
Eric Erdkamp ◽  
Andreas Ernst ◽  
Carl Hemprich ◽  
Leif C. Kröger ◽  
...  
Keyword(s):  
Rate Constants ◽  
Reaction Mechanisms ◽  
Urethane Formation ◽  
Cleavage Reactions

scholarly journals Recent advances in understanding oxygen evolution reaction mechanisms over iridium oxide

2021 ◽  
Author(s):  
Takahiro Naito ◽  
Tatsuya Shinagawa ◽  
Takeshi Nishimoto ◽  
Kazuhiro Takanabe
Keyword(s):  
Reaction Mechanism ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Reaction Mechanisms ◽  
State Of The Art ◽  
Iridium Oxide ◽  
The State ◽  
Computational Studies ◽  
Recent Advances ◽  
Iridium Oxides

Recent spectroscopic and computational studies concerning the oxygen evolution reaction over iridium oxides are reviewed to provide the state-of-the-art understanding of its reaction mechanism.

scholarly journals Experimental validation of the reaction mechanism models of dechlorination and [Zn] reclaiming in the roasting steelmaking zinc-rich dust process

2020 ◽  
Vol 39 (1) ◽  
pp. 107-116
Author(s):  
Hongyang Wang ◽  
Kai Dong ◽  
Rong Zhu
Keyword(s):  
Reaction Mechanism ◽  
Dust Particle ◽  
Chemical Reaction ◽  
Reaction Mechanisms ◽  
Experimental Validation ◽  
Step Process ◽  
Mass Percent ◽  
Mechanism Model ◽  
Air Atmosphere ◽  
Almost All

AbstractThe reaction mechanism models of dechlorination and [Zn] reclaiming in the roasting steelmaking zincrich dust process are studied. The dust collected from a steelwork contains 63.8% zinc and 3.18% chlorine (mass percent), of which, almost all zinc elements exist in ZnO and ZnCl2 forms, and all the chlorine elements are stored in ZnCl2. When the dust is roasted at above 732∘C in an air atmosphere, the ZnCl2 in the steelmaking zinc-rich dust is volatilized into steam and then oxidized into ZnO. Finding the position where the chemical reaction occurs is the key to determining the reaction mechanisms of dechlorination and [Zn] reclaiming. In this study, two groups of thermal experiments are designed and executed for roasting in different atmosphere environments and at different roasting temperatures. Based on the experiment results, the mechanism model is discussed and built, and the reaction of dechlorination and [Zn] reclaiming is shown to be a multi-step process. Because O2 from the air cannot transmit into the dust particle interior or dust bed effectively, the chemical reaction of [Zn] reclaiming occurs in the external gas environment outside of the dust, where the [Zn] recalcining reaction should be limited by the dynamics of new nucleation of ZnO solids.

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