Effect of product inhibition on kinetics of drug elimination

1973 ◽  
Vol 1 (3) ◽  
pp. 231-242 ◽  
Author(s):  
Donald Perrier ◽  
John J. Ashley ◽  
Gerhard Levy
Keyword(s):  
Product Inhibition ◽  
Drug Elimination ◽  
Kinetics Of

scholarly journals The kinetic mechanism of the major form of ox kidney aldehyde reductase with d-glucuronic acid

1982 ◽  
Vol 205 (2) ◽  
pp. 381-388 ◽  
Author(s):  
Ann K. Daly ◽  
Timothy J. Mantle
Keyword(s):  
Glucuronic Acid ◽  
Alternative Pathway ◽  
Kinetic Mechanism ◽  
Product Inhibition ◽  
Aldehyde Reductase ◽  
Major Form ◽  
Mechanism Of Inhibition ◽  
Steady State Kinetics ◽  
Inhibition Studies ◽  
Kinetics Of

The steady-state kinetics of the major form of ox kidney aldehyde reductase with d-glucuronic acid have been determined at pH7. Initial rate and product inhibition studies performed in both directions are consistent with a Di-Iso Ordered Bi Bi mechanism. The mechanism of inhibition by sodium valproate and benzoic acid is shown to involve flux through an alternative pathway.

Phase-plane geometries in enzyme kinetics

1994 ◽  
Vol 72 (3) ◽  
pp. 800-812 ◽  
Author(s):  
Simon J. Fraser ◽  
Marc R. Roussel
Keyword(s):  
Steady State ◽  
Phase Plane ◽  
Competitive Inhibition ◽  
Three Dimensional ◽  
Product Inhibition ◽  
Slow Manifold ◽  
Dimensional System ◽  
Planar System ◽  
State Behaviour ◽  
Kinetics Of

The transient and steady-state behaviour of the reversible Michaelis–Menten mechanism [R] and Competitive Inhibition (CI) mechanism is studied by analysis in the phase plane. Usually, the kinetics of both mechanisms is simplified to give a modified Michaelis–Menten velocity expression; this applies to the CI mechanism with excess inhibitor and to mechanism [R] in the product inhibition limit. In this paper, [R] is treated exactly as a plane autonomous system of differential equations and its true (dynamical) steady state is described by a line-like slow manifold M. Initial velocity experiments for [R] no longer strictly correspond to the hyperbolic law (as in the irreversible Michaelis–Menten mechanism) and this leads to corrections to the standard integrated rate law. Using a new analysis, the slow dynamics of the CI mechanism is reduced from a three-dimensional system to a planar system. In this mechanism transient decay collapses the trajectory flow onto a two-dimensional "slow" surface Σ; motion on Σ can be treated exactly as projected dynamics in the plane. This projected flow may differ in important ways from that of two-step mechanisms, e.g., it may lack a proper steady state. The relevance of these more accurate dynamical descriptions is discussed in relation to experimental design and metabolic function.

scholarly journals Product Inhibition and pH Affect Stoichiometry and Kinetics of Chain Elongating Microbial Communities in Sequencing Batch Bioreactors

2021 ◽  
Vol 9 ◽  
Author(s):  
Maximilienne Toetie Allaart ◽  
Gerben Roelandt Stouten ◽  
Diana Z. Sousa ◽  
Robbert Kleerebezem
Keyword(s):  
Microbial Communities ◽  
Amplicon Sequencing ◽  
Short Chain Fatty Acids ◽  
Product Inhibition ◽  
Chain Elongation ◽  
Rrna Gene ◽  
Specific Substrate ◽  
Substrate Uptake ◽  
Ph Values ◽  
Kinetics Of

Anaerobic microbial communities can produce carboxylic acids of medium chain length (e.g., caproate, caprylate) by elongating short chain fatty acids through reversed β-oxidation. Ethanol is a common electron donor for this process. The influence of environmental conditions on the stoichiometry and kinetics of ethanol-based chain elongation remains elusive. Here, a sequencing batch bioreactor setup with high-resolution off-gas measurements was used to identify the physiological characteristics of chain elongating microbial communities enriched on acetate and ethanol at pH 7.0 ± 0.2 and 5.5 ± 0.2. Operation at both pH-values led to the development of communities that were highly enriched (>50%, based on 16S rRNA gene amplicon sequencing) in Clostridium kluyveri related species. At both pH-values, stably performing cultures were characterized by incomplete substrate conversion and decreasing biomass-specific hydrogen production rates during an operational cycle. The process stoichiometries obtained at both pH-values were different: at pH 7.0, 71 ± 6% of the consumed electrons were converted to caproate, compared to only 30 ± 5% at pH 5.5. Operating at pH 5.5 led to a decrease in the biomass yield, but a significant increase in the biomass-specific substrate uptake rate, suggesting that the organisms employ catabolic overcapacity to deal with energy losses associated to product inhibition. These results highlight that chain elongating conversions rely on a delicate balance between substrate uptake- and product inhibition kinetics.

The kinetics of end-product inhibition of l-lactate production from xylose and glucose by Lactococcus lactis IO-1

1993 ◽  
Vol 15 (5) ◽  
pp. 489-494 ◽  
Author(s):  
Ayaaki Ishizaki ◽  
Tomoko Ueda ◽  
Kenji Tanaka ◽  
Peter F. Stanbury
Keyword(s):  
Lactococcus Lactis ◽  
Lactate Production ◽  
Product Inhibition ◽  
Kinetics Of

scholarly journals A product-inhibition study of the mechanism of mitochondrial octanoyl-coenzyme A synthetase

1969 ◽  
Vol 111 (3) ◽  
pp. 257-262 ◽  
Author(s):  
A. B. Graham ◽  
M. V. Park
Keyword(s):  
Coenzyme A ◽  
Liver Mitochondria ◽  
Product Inhibition ◽  
Inhibition Kinetics ◽  
Inhibition Study ◽  
Ping Pong ◽  
Kinetics Of ◽  
Allosteric Activator

By a study of the product-inhibition kinetics of the octanoyl-CoA synthetase from ox liver mitochondria, evidence was obtained consistent with the hypothesis that the enzyme reacts by a Bi Uni Uni Bi Ping Pong type of mechanism in which the order of addition and evolution of substrates and products is CoA, octanoate, octanoyl-CoA, ATP, PPi and AMP. There is also evidence that more than one molecule of CoA can add to the enzyme and that it may act as an allosteric activator.

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