The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Robert A Alberty - One of the best experts on this subject based on the ideXlab platform.
-
Estimation of kinetic parameters when modifiers are bound in Enzyme-Catalyzed Reactions.
The journal of physical chemistry. B, 2010Co-Authors: Robert A AlbertyAbstract:Modifiers of Enzyme-Catalyzed Reactions can have various types of effects on the velocity, but the most important effect is that they provide multiple pathways to products. The rapid-equilibrium kinetic effects of modifiers are explored for the Enzyme-Catalyzed Reaction A --> products. When a single molecule of modifier X is bound, the mechanism involves three independent equilibrium expressions and two rate constants. But when two molecules of X are bound are bound in two Reactions, there are five independent equilibria and three paths to products. The advantages of using a computer to derive rapid-equilibrium rate equations are that more complicated rate equations can be derived and the kinetic parameters can be estimated using the minimum number of velocity measurements. The mechanism with three paths to products is of special interest because the effects of cooperativity can be studied. Thermodynamic cycles can be used to estimate additional kinetic parameters.
-
determination of rapid equilibrium kinetic parameters of ordered and random Enzyme Catalyzed Reaction a b p q
Journal of Physical Chemistry B, 2009Co-Authors: Robert A AlbertyAbstract:This article deals with the rapid-equilibrium kinetics of the forward and reverse Reactions together for the ordered and random Enzyme-Catalyzed A + B = P + Q and emphasizes the importance of reporting the values of the full set of equilibrium constants. Equilibrium constants that are not in the rate equation can be calculated for random mechanisms using thermodynamic cycles. This treatment is based on the use of a computer to derive rate equations for three mechanisms and to estimate the kinetic parameters with the minimum number of velocity measurements. The most general of these three programs is the one to use first when the mechanism for A + B = P + Q is studied for the first time. This article shows the effects of experimental errors in velocity measurements on the values of the kinetic parameters and on the apparent equilibrium constant calculated using the Haldane relation.
-
Changes in the standard transformed thermodynamic properties of Enzyme-Catalyzed Reactions with ionic strength.
The journal of physical chemistry. B, 2007Co-Authors: Robert A AlbertyAbstract:The ionic strength has significant effects on the thermodynamic properties of ionic species and on the transformed thermodynamic properties of biochemical reactants at specified pH values. These effects are discussed for species, reactants, and Enzyme-Catalyzed Reactions. This has led to three new thermodynamic properties: (z(j)(2) - NH(j)), (z(2) - N(H))(i), and Delta(r)(z((2)-N(H)), which are referred to as ionic strength coefficients. The first of these is a property of a species, the second is a property of a reactant, and the third is the property of an Enzyme-Catalyzed Reaction. The effects of ionic strength on standard thermodynamic properties of species, standard transformed thermodynamic properties of reactants, and standard transformed thermodynamic properties of Enzyme-Catalyzed Reactions are proportional to these new thermodynamic properties.
-
Components and coupling in Enzyme-Catalyzed Reactions.
The journal of physical chemistry. B, 2005Co-Authors: Robert A AlbertyAbstract:Many Enzyme-Catalyzed Reactions involve coupling of two or more Reactions that could otherwise be Catalyzed separately. When biochemical Reactions are coupled, the equilibrium composition is very different from that when the Reactions are not coupled. The number of components in a chemical Reaction is equal to the number of independent conservation equations for atoms of elements, but the number of components in an Enzyme-Catalyzed Reaction that is coupled is larger than the number of independent conservation equations for atoms of elements. The investigation of these additional conservation equations by use of linear algebra is complicated by the fact that in dilute aqueous solutions, the activity of water is taken to be unity. This causes an incompatibility of conservation matrices and stoichiometric number matrices that can be avoided by use of the further transformed Gibbs energy G' ' that provides the criterion for spontaneous change and equilibrium when the standard transformed Gibbs energy of water is constant. In the most striking example discussed, the Enzyme mechanism of a ligase Reaction introduces three constraints in addition to conservation of atoms of elements. This is completely unheard of in chemical Reaction thermodynamics.
Guiyin Li - One of the best experts on this subject based on the ideXlab platform.
-
Colorimetric detection of 1,5-anhydroglucitol based on graphene quantum dots and Enzyme-Catalyzed Reaction
International Journal of Biological Macromolecules, 2018Co-Authors: Zhide Zhou, Wen Xue, Yunxiao Wang, Jiejing Chen, Le Zhao, Zhihong Wang, Jintao Liang, Yong Huang, Guiyin LiAbstract:Early diagnosis of diabetes yields significant clinical benefits. The serum level of 1,5‑anhydroglucitol (1,5‑AG) has been a new biochemical marker for postprandial hyperglycemia. In this study, a simple colorimetric method for 1,5‑AG detection has been designed based on highly efficient peroxidase mimetic activity of GQDs and Enzyme-Catalyzed Reaction. By the catalytic action of pyranose oxidase (PROD), the 1,5‑AG was oxidized to 1,5‑anhydrofuctose and H2O2. The GQDs in the presence of H2O2exhibited highly efficient catalytic activity toward the oxidation of 3, 3′ 5, 5′‑tetramethylbenzidine (TMB) to a blue colored product. The influence of relevant experimental variables was optimized. A linear relationship of optical signal with the concentration of 1,5‑AG in the range of 20.0–100.0 μg/mL with the regression correlation coefficient of 0.9985 was obtained which could be monitored by colorimetry detection. The limit of detection (LOD) for 1,5‑AG detection was approximately 0.144 μg/mL. All in all, the proposed 1,5‑AG detection system based on GQDs and PROD-Catalyzed Reaction showed better performances with simple operation, low-cost, higher selectivity.
Vickery L. Arcus - One of the best experts on this subject based on the ideXlab platform.
-
the inflection point hypothesis the relationship between the temperature dependence of Enzyme Catalyzed Reaction rates and microbial growth rates
Biochemistry, 2020Co-Authors: Erica J Prentice, Joanna L Hicks, Hendrik Ballerstedt, Lars M Blank, Liyin L Liang, Louis A Schipper, Vickery L. ArcusAbstract:The temperature dependence of biological rates at different scales (from individual Enzymes to isolated organisms to ecosystem processes such as soil respiration and photosynthesis) is the subject of much historical and contemporary research. The precise relationship between the temperature dependence of Enzyme rates and those at larger scales is not well understood. We have developed macromolecular rate theory (MMRT) to describe the temperature dependence of biological processes at all scales. Here we formalize the scaling relationship by investigating MMRT both at the molecular scale (constituent Enzymes) and for growth of the parent organism. We demonstrate that the inflection point (Tinf) for the temperature dependence of individual metabolic Enzymes coincides with the optimal growth temperature for the parent organism, and we rationalize this concordance in terms of the necessity for linearly correlated rates for metabolic Enzymes over fluctuating environmental temperatures to maintain homeostasis. Indeed, Tinf is likely to be under strong selection pressure to maintain coordinated rates across environmental temperature ranges. At temperatures at which rates become uncorrelated, we postulate a regulatory catastrophe and organism growth rates precipitously decline at temperatures where this occurs. We show that the curvature in the plots of the natural log of the rate versus temperature for individual Enzymes determines the curvature for the metabolic process overall and the curvature for the temperature dependence of the growth of the organism. We have called this "the inflection point hypothesis", and this hypothesis suggests many avenues for future investigation, including avenues for engineering the thermal tolerance of organisms.
-
Temperature, Dynamics, and Enzyme-Catalyzed Reaction Rates
Annual review of biophysics, 2020Co-Authors: Vickery L. Arcus, Adrian J MulhollandAbstract:We review the adaptations of Enzyme activity to different temperatures. Psychrophilic (cold-adapted) Enzymes show significantly different activation parameters (lower activation enthalpies and entr...
Gautam Gangopadhyay - One of the best experts on this subject based on the ideXlab platform.
-
Power law kinetics in reversible Enzyme-Catalyzed Reaction due to diffusion
The Journal of Chemical Physics, 2003Co-Authors: Sujata Paul, Gautam GangopadhyayAbstract:The effect of diffusion on the reversible Enzyme-Catalyzed Reaction is investigated. The kinetic scheme of the Enzyme-Catalyzed Reaction is considered with a little generalization of Michaelis–Menten mechanism where the last step is taken as reversible. By using a fluctuation theory approach we have considered the relaxation mechanism where the quadratic nonlinearity of the equation of fluctuation around the equilibrium acts as a small perturbation. In three dimensions, the effect of diffusion is reflected through the relaxation kinetics of the Reaction as a power law asymptotics, t−3/2, when the system approaches equilibrium.
Zhide Zhou - One of the best experts on this subject based on the ideXlab platform.
-
Colorimetric detection of 1,5-anhydroglucitol based on graphene quantum dots and Enzyme-Catalyzed Reaction
International Journal of Biological Macromolecules, 2018Co-Authors: Zhide Zhou, Wen Xue, Yunxiao Wang, Jiejing Chen, Le Zhao, Zhihong Wang, Jintao Liang, Yong Huang, Guiyin LiAbstract:Early diagnosis of diabetes yields significant clinical benefits. The serum level of 1,5‑anhydroglucitol (1,5‑AG) has been a new biochemical marker for postprandial hyperglycemia. In this study, a simple colorimetric method for 1,5‑AG detection has been designed based on highly efficient peroxidase mimetic activity of GQDs and Enzyme-Catalyzed Reaction. By the catalytic action of pyranose oxidase (PROD), the 1,5‑AG was oxidized to 1,5‑anhydrofuctose and H2O2. The GQDs in the presence of H2O2exhibited highly efficient catalytic activity toward the oxidation of 3, 3′ 5, 5′‑tetramethylbenzidine (TMB) to a blue colored product. The influence of relevant experimental variables was optimized. A linear relationship of optical signal with the concentration of 1,5‑AG in the range of 20.0–100.0 μg/mL with the regression correlation coefficient of 0.9985 was obtained which could be monitored by colorimetry detection. The limit of detection (LOD) for 1,5‑AG detection was approximately 0.144 μg/mL. All in all, the proposed 1,5‑AG detection system based on GQDs and PROD-Catalyzed Reaction showed better performances with simple operation, low-cost, higher selectivity.