scholarly journals The steady-state kinetics of isotope exchange for one substrate–one product enzymic reactions

1973 ◽  
Vol 135 (4) ◽  
pp. 861-866 ◽  
Author(s):  
Ivan G. Darvey
Keyword(s):  
Steady State ◽  
Isotope Exchange ◽  
Kinetic Equations ◽  
Enzyme Reaction ◽  
Radioactive Material ◽  
First Order ◽  
Steady State Kinetics ◽  
The One ◽  
Allosteric Mechanisms ◽  
Kinetics Of

Steady-state kinetic equations for isotope exchange are derived for a number of one substrate–one product enzymic mechanisms in which two molecules of substrate or product can be combined with an enzyme molecule at the one time (e.g. allosteric mechanisms). The usual assumption, that the radioactive material is distributed among the substrate and product components according to a first-order law, is not valid. One can recognize whether isotope-exchange kinetics of an enzyme reaction follows first-order behaviour by using various initial concentrations of the labelled substance added to a mixture.

scholarly journals The steady-state kinetics of isotope exchange at equilibrium: one substrate–one product enzymic mechanisms where two molecules of substrate or product are bound to an enzyme molecule (Short Communication)

1974 ◽  
Vol 143 (3) ◽  
pp. 783-784
Author(s):  
Ivan G. Darvey
Keyword(s):  
Steady State ◽  
Isotope Exchange ◽  
Short Communication ◽  
Enzyme Molecule ◽  
First Order ◽  
Steady State Kinetics ◽  
The One ◽  
Kinetics Of

The conclusion that the steady-state kinetics of isotope exchange at equilibrium do not show first-order behaviour for some one substrate–one product enzymic mechanisms in which two molecules of substrate or product can be combined with an enzyme molecule at the one time was shown to be erroneous.

scholarly journals Theoretical approach to the steady-state kinetics of a bi-substrate acyl-transfer enzyme reaction that follows a hydrolysable-acyl-enzyme-based mechanism. Application to the study of lysophosphatidylcholine:lysophosphatidylcholine acyltransferase from rabbit lung

1990 ◽  
Vol 266 (1) ◽  
pp. 47-53 ◽  
Author(s):  
J Martín ◽  
J Pérez-Gil ◽  
C Acebal ◽  
R Arche
Keyword(s):  
Steady State ◽  
Kinetic Equations ◽  
Enzyme Reaction ◽  
Great Accuracy ◽  
Acyl Transfer ◽  
Rabbit Lung ◽  
Steady State Kinetics ◽  
Kinetic Pattern ◽  
Covalent Intermediate ◽  
Kinetics Of

A kinetic model is proposed for catalysis by an enzyme that has several special characteristics: (i) it catalyses an acyl-transfer bi-substrate reaction between two identical molecules of substrate, (ii) the substrate is an amphiphilic molecule that can be present in two physical forms, namely monomers and micelles, and (iii) the reaction progresses through an acyl-enzyme-based mechanism and the covalent intermediate can react also with water to yield a secondary hydrolytic reaction. The theoretical kinetic equations for both reactions were deduced according to steady-state assumptions and the theoretical plots were predicted. The experimental kinetics of lysophosphatidylcholine:lysophosphatidylcholine acyltransferase from rabbit lung fitted the proposed equations with great accuracy. Also, kinetics of inhibition by products behaved as expected. It was concluded that the competition between two nucleophiles for the covalent acyl-enzyme intermediate, and not a different enzyme action depending on the physical state of the substrate, is responsible for the differences in kinetic pattern for the two activities of the enzyme. This conclusion, together with the fact that the kinetic equation for the transacylation is quadratic, generates a ‘hysteretic’ pattern that can provide the basis of self-regulatory properties for enzymes to which this model could be applied.

The Kinetics of Glucose Decomposition with Sulfate Reduction in the Anaerobic Fluidized Bed Reactor

1993 ◽  
Vol 28 (2) ◽  
pp. 135-144 ◽  
Author(s):  
S. Matsui ◽  
R. Ikemoto Yamamoto ◽  
Y. Tsuchiya ◽  
B. Inanc
Keyword(s):  
Sulfate Reduction ◽  
Fluidized Bed ◽  
Kinetic Equations ◽  
Fluidized Bed Reactor ◽  
Order Reaction ◽  
First Order Reaction ◽  
First Order ◽  
Glucose Decomposition ◽  
Reaction Equations ◽  
Kinetics Of

Using a fluidized bed reactor, experiments on glucose decomposition with and without sulfate reduction were conducted. Glucose in the reactor was mainly decomposed into lactate and ethanol. Lactate was mainly decomposed into propionate and acetate, while ethanol was decomposed into propionate, acetate, and hydrogen. Sulfate reduction was not involved in the decomposition of glucose, lactate, and ethanol, but was related to propionate and acetate decomposition. The stepwise reactions were modeled using either a Monod expression or first order reaction kinetics in respect to the reactions. The coefficients of the kinetic equations were determined experimentally. The modified Monod and first order reaction equations were effective at predicting concentrations of glucose, lactate, ethanol, propionate, acetate, and sulfate along the beight of the reactor. With sulfate reduction, propionate was decomposed into acetate, while without sulfate reduction, accumulation of propionate was observed in the reactor. Sulfate reduction accelerated propionate conversion into acetate by decreasing the hydrogen concentration.

scholarly journals Kinetics of Biofilm Detachment

1992 ◽  
Vol 26 (9-11) ◽  
pp. 1995-1998 ◽  
Author(s):  
B. M. Peyton ◽  
W. G. Characklis
Keyword(s):  
Steady State ◽  
Utilization Rate ◽  
Carbon Utilization ◽  
Biofilm Thickness ◽  
First Order ◽  
Detachment Rate ◽  
Biofilm Detachment ◽  
Biofilm Modeling ◽  
Kinetics Of ◽  
Sensitive Variable

In predictive biofilm modeling, the detachment rate coefficient may be the most sensitive variable affecting both the predicted rate and the extent of biofilm accumulation. At steady state the detachment rate must be equal to the net growth rate in the biofilm. In systems where organic carbon is growth-limiting, the substrate carbon utilization rate determines the net biomass production rate and, therefore, the steady state biomass detachment rate. Detachment rates, first order with biofilm thickness, fit the experimental data well, but are not predictive since the coefficients must be determined experimentally.

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