scholarly journals Mechanism of a Disassembly Driven Sensing System Studied by Stopped-Flow Kinetics

2021 ◽  
Author(s):  
Cara Gallo ◽  
Suma S. Thomas ◽  
Allison Selinger ◽  
Fraser Hof ◽  
Cornelia Bohne
Keyword(s):  
Steady State ◽  
Rate Constants ◽  
Artificial Saliva ◽  
Global Analysis ◽  
Dissociation Rate ◽  
Stopped Flow ◽  
Steady State Fluorescence ◽  
Saliva Analysis ◽  
Binding Isotherms ◽  
Dissociation Rate Constants

<div> Mechanistic studies were carried out on the kinetics for the assembly of a DimerDye (DD12) and the binding of the monomeric DimerDye (DD1) with nicotine in aqueous buffer and artificial saliva. DD12 is non-fluorescent, while monomeric DD1 and DD1-nicotine fluoresce. Binding isotherms were determined from steady-state fluorescence experiments. The report includes measurements of the steady-state fluorescence at pHs 2.2, 6.3 and 12.1, and stopped-flow kinetic data for the homodimerization forming DD12 and DD1-nicotine formation in buffer and artificial saliva. Analysis of the homodimerization kinetics led to the recovery of the association and dissociation rate constants for DD12. These rate constants were used in the global analysis for the coupled kinetics for DD1-nicotine formation, which led to the determination of the association and dissociation rate constants for nicotine binding to DD1.</div>

scholarly journals Mechanism of a Disassembly Driven Sensing System Studied by Stopped-Flow Kinetics

2021 ◽  
Author(s):  
Cara Gallo ◽  
Suma S. Thomas ◽  
Allison Selinger ◽  
Fraser Hof ◽  
Cornelia Bohne
Keyword(s):  
Steady State ◽  
Rate Constants ◽  
Artificial Saliva ◽  
Global Analysis ◽  
Dissociation Rate ◽  
Stopped Flow ◽  
Steady State Fluorescence ◽  
Saliva Analysis ◽  
Binding Isotherms ◽  
Dissociation Rate Constants

<div> Mechanistic studies were carried out on the kinetics for the assembly of a DimerDye (DD12) and the binding of the monomeric DimerDye (DD1) with nicotine in aqueous buffer and artificial saliva. DD12 is non-fluorescent, while monomeric DD1 and DD1-nicotine fluoresce. Binding isotherms were determined from steady-state fluorescence experiments. The report includes measurements of the steady-state fluorescence at pHs 2.2, 6.3 and 12.1, and stopped-flow kinetic data for the homodimerization forming DD12 and DD1-nicotine formation in buffer and artificial saliva. Analysis of the homodimerization kinetics led to the recovery of the association and dissociation rate constants for DD12. These rate constants were used in the global analysis for the coupled kinetics for DD1-nicotine formation, which led to the determination of the association and dissociation rate constants for nicotine binding to DD1.</div>

scholarly journals Simplifications of the derivations and forms of steady-state equations for non-equilibrium random substrate-modifier and allosteric enzyme mechanisms

1976 ◽  
Vol 159 (3) ◽  
pp. 449-456 ◽  
Author(s):  
E P Whitehead
Keyword(s):  
Steady State ◽  
Rate Constants ◽  
Dissociation Rate ◽  
Partial Ordering ◽  
British Library ◽  
Quasi Equilibrium ◽  
State Equations ◽  
Allosteric Enzyme ◽  
Dissociation Rate Constants ◽  
Alternative Routes

The steady-state equations for “random” enzymic mechanisms (ones with alternative routes for substrate and enzyme to form enzyme-substrate complexes) are non-Michaelian and very complicated when a quasi-equilibrium approximation cannot be used. General methods for simplifying their forms and derivations are given and applied to several single-substrate mechanisms of general or topical interest. The special simplifications resulting from partial ordering of reaction mechanism, from gross inequalities of rate constants, and from special relationships between catalytic and dissociation rate constants, are considered with reference to allosteric mechanisms. Some equations mentioned, but not given here, and more detailed working out of some of those given, have been deposited as Supplementary Publication SUP 50069 (18 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms given in Biochem. J. (1976) 153, 5.

scholarly journals Dissociation Rate Constants of Human Fibronectin Binding to Fibronectin-binding Proteins on LivingStaphylococcus aureusIsolated from Clinical Patients

2012 ◽  
Vol 287 (9) ◽  
pp. 6693-6701 ◽  
Author(s):  
Nadia N. Casillas-Ituarte ◽  
Brian H. Lower ◽  
Supaporn Lamlertthon ◽  
Vance G. Fowler ◽  
Steven K. Lower
Keyword(s):  
Rate Constants ◽  
Binding Proteins ◽  
Dissociation Rate ◽  
Human Fibronectin ◽  
Fibronectin Binding ◽  
Dissociation Rate Constants

scholarly journals Head-to-tail polymerization of microtubules in vitro. Electron microscope analysis of seeded assembly.

1980 ◽  
Vol 84 (1) ◽  
pp. 141-150 ◽  
Author(s):  
L G Bergen ◽  
G G Borisy
Keyword(s):  
Electron Microscope ◽  
Rate Constants ◽  
Dissociation Constants ◽  
Dissociation Rate ◽  
Association Constants ◽  
Directional Growth ◽  
Microtubule Protein ◽  
Electron Microscope Analysis ◽  
Dissociation Rate Constants

Microtubules are polar structures, and this polarity is reflected in their biased directional growth. Following a convention established previously (G. G. Borisy, 1978, J. Mol. Biol. 124:565--570), we define the plus (+) and minus (-) ends of a microtubule as those equivalent in structural orientation to the distal and proximal ends, respectively, of the A subfiber of flagellar outer doublets. Rates of elongation were obtained for both ends using flagellar axonemes as seeds and porcine brain microtubule protein as subunits. Since the two ends of a flagellar seed are distinguishable morphologically, elongation of each end may be analyzed separately. By plotting rates of elongation at various concentrations of subunit protein, we have determined the association and dissociation rate constants for the plus and minus ends. Under our conditions at 30 degrees C, the association constants were 7.2 X 10(6) M-1 s-1 and 2.25 X 10(6) M-1 s-1 for the plus and minus ends, respectively, and the dissociation constants were 17 s-1 and 7 s-1. From these values and Wegner's equations (1976, J. Mol. Biol. 108:139--150), we identified the plus end of the microtubule as its head and calculated "s," the head-to-tail polymerization parameter. Surprisingly small values (s = 0.07 +/- 0.02) were found. The validity of models of mitosis based upon head-to-tail polymerization (Margolis et al., 1978, Nature (Lond.) 272:450--452) are discussed in light of a small value for s.

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