Random-Order Ternary Complex Reaction Mechanism of Serine Acetyltransferase fromEscherichia coli

Biochemistry ◽  
2003 ◽  
Vol 42 (10) ◽  
pp. 3113-3119 ◽  
Author(s):  
V. John Hindson ◽  
William V. Shaw
Keyword(s):  
Reaction Mechanism ◽  
Ternary Complex ◽  
Random Order ◽  
Complex Reaction ◽  
Serine Acetyltransferase ◽  
Fromescherichia Coli

scholarly journals Serine acetyltransferase of Escherichia coli: substrate specificity and feedback control by cysteine

2003 ◽  
Vol 375 (3) ◽  
pp. 745-752 ◽  
Author(s):  
V. John HINDSON
Keyword(s):  
Escherichia Coli ◽  
Steady State ◽  
Reaction Mechanism ◽  
Binding Site ◽  
Ternary Complex ◽  
Random Order ◽  
Hydroxyl Group ◽  
Acyl Donor ◽  
Complex Reaction ◽  
Serine Acetyltransferase

Although SAT (serine acetyltransferase) of Escherichia coli, which catalyses the first step in cysteine synthesis, proceeds via a random-order ternary complex reaction mechanism [Hindson and Shaw (2003) Biochemistry 42, 3113–3119], it has been suggested that the nearly identical enzyme from Salmonella typhimurium might involve an acetyl-enzyme intermediate [Leu and Cook (1994) Protein Peptide Lett. 1, 157–162]. In this study the alternative acetyl acceptor threonine and the alternative acyl donor, propionyl-CoA were used to further investigate the reaction mechanism of SAT from E. coli. Steady-state kinetic data and dead-end inhibition studies were again diagnostic of a random-order ternary complex reaction mechanism for alternative substrates. Since earlier kinetic studies with SAT from S. typhimurium suggested that cysteine competes with acetyl-CoA for binding, rather than serine with which it is isostructural, the specificity of the serine-binding pocket was assessed with three substrate mimics; β-hydroxypropionic acid, glycine and ethanolamine. The data show that SAT interacts productively with the amino and hydroxymethyl moieties of serine, whereas the carboxyl group provides an essential contribution to binding strongly, supporting a view that cysteine will interact productively at the serine-binding site. Furthermore, since the hydroxymethyl contact region of the serine-binding site appears able to accommodate the methylene and acetyl moeties of threonine and O-acetyl-serine respectively, the site is unlikely to provide obligatory short-range contacts with the hydroxyl group of serine, a prerequisite for exclusion of cysteine. Such a proposal is supported by the results of micro-calorimetric studies which show that cysteine competes with serine for binding to SAT rather than with CoA. It follows that tight binding of cysteine at the serine-binding site near the catalytic centre may be the effector of a substantial reduction in the affinity of SAT for CoA, yielding the observed pattern of steady-state inhibition and the mechanism by which cysteine mediates effective end-product control of its synthesis.

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 A kinetic study of rabbit muscle pyruvate kinase

1973 ◽  
Vol 131 (2) ◽  
pp. 223-236 ◽  
Author(s):  
S. Ainsworth ◽  
N. Macfarlane
Keyword(s):  
Reaction Mechanism ◽  
Kinetic Study ◽  
Pyruvate Kinase ◽  
Random Order ◽  
Experimental Results ◽  
Rabbit Muscle ◽  
Dead End ◽  
Inhibition Constants ◽  
Muscle Pyruvate Kinase ◽  
Kinetics Of

The paper reports a study of the kinetics of the reaction between phosphoenolpyruvate, ADP and Mg2+ catalysed by rabbit muscle pyruvate kinase. The experimental results indicate that the reaction mechanism is equilibrium random-order in type, that the substrates and products are phosphoenolpyruvate, ADP, Mg2+, pyruvate and MgATP, and that dead-end complexes, between pyruvate, ADP and Mg2+, form randomly and exist in equilibrium with themselves and other substrate complexes. Values were determined for the Michaelis, dissociation and inhibition constants of the reaction and are compared with values ascertained by previous workers.

scholarly journals Unveiling the Rate-Limiting Step of the Bc1 Complex Reaction Mechanism

2019 ◽  
Vol 116 (3) ◽  
pp. 419a
Author(s):  
Angela M. Barragan ◽  
Alexander V. Soudackov ◽  
Zaida Luthey-Schulten ◽  
Klaus Schulten ◽  
Sharon Hammes-Schiffer ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Complex Reaction ◽  
Bc1 Complex ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting

Optimal control of a plug flow reactor with a complex reaction mechanism

1993 ◽  
Vol 97 (45) ◽  
pp. 11689-11695 ◽  
Author(s):  
Atipat Rojnuckarin ◽  
Christodoulos A. Floudas ◽  
Herschel Rabitz ◽  
Richard A. Yetter
Keyword(s):  
Optimal Control ◽  
Reaction Mechanism ◽  
Flow Reactor ◽  
Plug Flow ◽  
Plug Flow Reactor ◽  
Complex Reaction

scholarly journals A Glutathione S-Transferase Catalyzes the Dehalogenation of Inhibitory Metabolites of Polychlorinated Biphenyls

2006 ◽  
Vol 188 (12) ◽  
pp. 4424-4430 ◽  
Author(s):  
Pascal D. Fortin ◽  
Geoff P. Horsman ◽  
Hao M. Yang ◽  
Lindsay D. Eltis
Keyword(s):  
Reaction Mechanism ◽  
Polychlorinated Biphenyls ◽  
Ternary Complex ◽  
Physiological Function ◽  
Complex Mechanism ◽  
Glutathione S Transferase ◽  
Burkholderia Xenovorans ◽  
Pcb Metabolites

ABSTRACT BphK is a glutathione S-transferase of unclear physiological function that occurs in some bacterial biphenyl catabolic (bph) pathways. We demonstrated that BphK of Burkholderia xenovorans strain LB400 catalyzes the dehalogenation of 3-chloro 2-hydroxy-6-oxo-6-phenyl-2,4-dienoates (HOPDAs), compounds that are produced by the cometabolism of polychlorinated biphenyls (PCBs) by the bph pathway and that inhibit the pathway's hydrolase. A one-column protocol was developed to purify heterologously produced BphK. The purified enzyme had the greatest specificity for 3-Cl HOPDA (k cat/Km , ∼104 M−1 s−1), which it dechlorinated approximately 3 orders of magnitude more efficiently than 4-chlorobenzoate, a previously proposed substrate of BphK. The enzyme also catalyzed the dechlorination of 5-Cl HOPDA and 3,9,11-triCl HOPDA. By contrast, BphK did not detectably transform HOPDA, 4-Cl HOPDA, or chlorinated 2,3-dihydroxybiphenyls. The BphK-catalyzed dehalogenation proceeded via a ternary-complex mechanism and consumed 2 equivalents of glutathione (GSH) (Km for GSH in the presence of 3-Cl HOPDA, ∼0.1 mM). A reaction mechanism consistent with the enzyme's specificity is proposed. The ability of BphK to dehalogenate inhibitory PCB metabolites supports the hypothesis that this enzyme was recruited to facilitate PCB degradation by the bph pathway.

scholarly journals Hydrolysis of Guanosine Triphosphate (GTP) by the Ras·GAP Protein Complex: Reaction Mechanism and Kinetic Scheme

2015 ◽  
Vol 119 (40) ◽  
pp. 12838-12845 ◽  
Author(s):  
Maria G. Khrenova ◽  
Bella L. Grigorenko ◽  
Anatoly B. Kolomeisky ◽  
Alexander V. Nemukhin
Keyword(s):  
Reaction Mechanism ◽  
Protein Complex ◽  
Kinetic Scheme ◽  
Complex Reaction ◽  
Guanosine Triphosphate ◽  
Hydrolysis Of

scholarly journals A Plasmonic Approach to Study Protein Interaction Kinetics through the Dimerization of Functionalized Ag Nanoparticles

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Pablo A. Mercadal ◽  
Ruben D. Motrich ◽  
Eduardo A. Coronado
Keyword(s):  
Reaction Mechanism ◽  
Protein Interactions ◽  
Pair Interaction ◽  
Industrial Applications ◽  
Complex Reaction ◽  
Ag Nps ◽  
Vis Spectroscopy ◽  
Interaction Kinetics ◽  
Kinetics Of ◽  
Detection And Quantification

Abstract Understanding the kinetics of protein interactions plays a key role in biology with significant implications for the design of analytical methods for disease monitoring and diagnosis in medical care, research and industrial applications. Herein, we introduce a novel plasmonic approach to study the binding kinetics of protein-ligand interactions following the formation of silver nanoparticles (Ag NPs) dimers by UV-Vis spectroscopy that can be used as probes for antigen detection and quantification. To illustrate and test the method, the kinetics of the prototype biotin-streptavidin (Biot-STV) pair interaction was studied. Controlled aggregates (dimers) of STV functionalized Ag NPs were produced by adding stoichiometric quantities of gliadin-specific biotinylated antibodies (IgG-Biot). The dimerization kinetics was studied in a systematic way as a function of Ag NPs size and at different concentrations of IgG-Biot. The kinetics data have shown to be consistent with a complex reaction mechanism in which only the Ag NPs attached to the IgG-Biot located in a specific STV site are able to form dimers. These results help in elucidating a complex reaction mechanism involved in the dimerization kinetics of functionalized Ag NPs, which can serve as probes in surface plasmon resonance-based bioassays for the detection and quantification of different biomarkers or analytes of interest.

Balancing the chemical equations and their steady-state approximations in the complex reaction mechanism: linear algebra techniques

2020 ◽  
Vol 10 (12) ◽  
pp. 5247-5252 ◽  
Author(s):  
Faisal Sultan ◽  
Muhammad Shahzad ◽  
Mehboob Ali ◽  
Wajiha Adnan ◽  
Waqar Azeem Khan
Keyword(s):  
Steady State ◽  
Reaction Mechanism ◽  
Linear Algebra ◽  
Complex Reaction ◽  
Chemical Equations
Sign in / Sign up

Export Citation Format

Share Document