Photofragmentation of ketene to CH2(~X3B1) + CO. 1. Barrier height and dissociation rate constant

1990 ◽  
Vol 94 (1) ◽  
pp. 263-269 ◽  
Author(s):  
I Chia. Chen ◽  
C. Bradley. Moore
Keyword(s):  
Barrier Height ◽  
Rate Constant ◽  
Dissociation Rate ◽  
Dissociation Rate Constant

scholarly journals Protein-ligand dissociation rate constant from all-atom simulation

2021 ◽  
Author(s):  
Ekaterina Maximova ◽  
Eugene Postnikov ◽  
Anastasia Lavrova ◽  
Vladimir Farafonov ◽  
Dmitry Nerukh
Keyword(s):  
Molecular Dynamics ◽  
Rate Constant ◽  
Md Simulations ◽  
Dissociation Rate ◽  
Dissociation Rate Constant ◽  
Zero Force ◽  
Ligand Dissociation ◽  
Random Acceleration

Abstract Dissociation of a ligand isoniazid from a protein catalase was investigated using all-atom Molecular Dynamics (MD) simulations. Random Acceleration MD (τ-RAMD) was used where a random artificial force applied to the ligand facilitates its dissociation. We have suggested an approach to extrapolate such obtained dissociation times to the zero-force limit that was never attempted before, thus allowing direct comparison with experimentally measured values. We have found that our calculated dissociation time was equal to 36.1 seconds with statistically significant values distributed in the interval 0.2-72.0 s, that quantitatively matches the experimental value of 50 ± 8 seconds despite the extrapolation over nine orders of magnitude in time.

scholarly journals A sequence-specific threading tetra-intercalator with an extremely slow dissociation rate constant

2011 ◽  
Vol 3 (11) ◽  
pp. 875-881 ◽  
Author(s):  
Garen G. Holman ◽  
Maha Zewail-Foote ◽  
Amy Rhoden Smith ◽  
Kenneth A. Johnson ◽  
Brent L. Iverson
Keyword(s):  
Rate Constant ◽  
Dissociation Rate ◽  
Dissociation Rate Constant ◽  
Slow Dissociation

scholarly journals Reversibility in radionuclide/bentonite bulk and colloidal ternary systems

2015 ◽  
Vol 79 (6) ◽  
pp. 1307-1315 ◽  
Author(s):  
Nick Sherriff ◽  
Ragiab Issa ◽  
Katherine Morris ◽  
Francis Livens ◽  
Sarah Heath ◽  
...  
Keyword(s):  
Rate Constant ◽  
Ethylenediaminetetraacetic Acid ◽  
Average Rate ◽  
Ternary Systems ◽  
Dissociation Rate ◽  
Convincing Evidence ◽  
Dissociation Rate Constant ◽  
Stage Process ◽  
Slow Dissociation ◽  
The Eu

AbstractTernary systems of 152Eu(III), bulk bentonite and ethylenediaminetetraacetic acid (EDTA) ([Eu] = 7.9 × 10–10 M; pH = 6.0–7.0) have been studied. Without EDTA, there was slow uptake in a two-stage process, with initial rapid sorption of Eu(III) (96%), followed by slower uptake of a much smaller fraction (3.0% over a period of one month). The reversibility of Eu(III) binding was tested by allowing Eu(III) to sorb to bentonite for 1–322 days. EDTA was added to the pre-equilibrated Eu bentonite systems at 0.01 M, a concentration that was sufficient to suppress sorption in a system where EDTA was present prior to the contact of Eu(III) with bentonite. A fraction of the Eu was released instantaneously (30–50%), but a significant amount remained bound. With time, the amount of Eu(III) retained by the bentonite reduced, with a slow fraction dissociation rate constant of approximately 4.3 × 10–8 s–1 (values in the range 2.2 × 10–8 – 1.0 × 10–7 s–1) for pre-equilibration times ≥7 days. Eventually, the amount of Eu(III) remaining bound to the bentonite was within error of that when EDTA was present prior to contact (4.5% ± 0.6), although in systems with pre-equilibration times >100 days, full release took up to 500 days. Europium interactions with colloidal bentonite were also studied, and the dissociation rate constant measured by a resin competition method. For the colloids, more Eu was found in the slowly dissociating fraction (60–70%), but the first-order dissociation rate constant was faster, with an average rate constant of 8.8 × 10–7 s–1 and a range of 7.7 × 10–7 –9.5 × 10–7 s–1. For both bulk and colloidal bentonite, although slow dissociation was observed for Eu(III), there was no convincing evidence for 'irreversible' binding.

Protein–Ligand Dissociation Rate Constant from All-Atom Simulation

2021 ◽  
pp. 10631-10636
Author(s):  
Ekaterina Maximova ◽  
Eugene B. Postnikov ◽  
Anastasia I. Lavrova ◽  
Vladimir Farafonov ◽  
Dmitry Nerukh
Keyword(s):  
Rate Constant ◽  
Dissociation Rate ◽  
Dissociation Rate Constant ◽  
Ligand Dissociation

scholarly journals The rates of formation and dissociation of actin-myosin complexes. Effects of solvent, temperature, nucleotide binding and head-head interactions

1982 ◽  
Vol 203 (2) ◽  
pp. 453-460 ◽  
Author(s):  
S B Marston
Keyword(s):  
Rate Constant ◽  
Protein Concentration ◽  
Order Rate Constant ◽  
Dissociation Rate ◽  
Dissociation Rate Constant ◽  
Light Scatter ◽  
Association Rate Constant ◽  
Heavy Meromyosin ◽  
Association Rate ◽  
Low Protein

The rates of formation and dissociation of actin-subfragment 1 and actin-heavy mero-myosin complexes were measured by using light-scatter and the change in fluorescence of N-iodoacetyl-N'-(5-sulpho-1-naphthyl)ethylenediamine (IAEDANS)-labelled acting as probes. Association rate measurements were made at low protein concentration, where the transients approximated to single exponentials with rate constants proportional to the concentration of reactant in excess. Dissociation rate measurements were made by displacing IAEDANS-actin from myosin with excess native actin and by a salt jump. The second-order rate constant of association for actin-subfragment 1 was 3 × 10(6) M-1 . s-1 in 60 mM-KCl at 13 degree C. It was decreased 10-fold in 500 mM-KCl and in 50% (v/v) glycol. It was decreased 6-fold when MgADP or Mg[beta gamma-imido]ATP bound to myosin. The dissociation rate constant was 0.012 s-1 in 60 mM-KCl at 13 degree C. It was increased 4-fold by 500 mM-KCl, 25-fold by 50% glycol, 8-fold by MgADP binding and 170-fold by Mg[beta gamma-imido]ATP binding. Ea for association was 70 kJ . mol-1 and for dissociation 35 kJ . mol-1. Heavy meromyosin associated at twice the rate observed for subfragment 1 and dissociated at less than one-twentieth of the rate for subfragment 1 (60 mM-KCl, 25 degree C), but when Mg[beta gamma-imido]ATP bound actin-heavy meromyosin dissociated at one-half the rate for subfragment 1. There were significant correlations between increase in the dissociation rate constant, decrease in binding constant and increase in magnitude of conformational change. The association rate constant did not correlate with any property of the actin-myosin complex.

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