scholarly journals A fluorescence stopped-flow kinetic study of the conformational activation of α-chymotrypsin and several mutants

2004 ◽  
Vol 13 (9) ◽  
pp. 2533-2540 ◽  
Author(s):  
Gert Verheyden ◽  
Janka Matrai ◽  
Guido Volckaert ◽  
Yves Engelborghs
Keyword(s):  
Kinetic Study ◽  
Stopped Flow

scholarly journals Stopped-flow kinetic study of the H2O2 oxidation of substrates catalyzed by microperoxidase-8

2001 ◽  
Vol 6 (8) ◽  
pp. 770-777 ◽  
Author(s):  
Hui-Chun Yeh ◽  
Jinn-Shyan Wang ◽  
Oliver Y. Su ◽  
Wann-Yin Lin
Keyword(s):  
Kinetic Study ◽  
Stopped Flow ◽  
H2o2 Oxidation ◽  
Microperoxidase 8

scholarly journals Kinetic study of catalytic CO 2 hydration by metal-substituted biomimetic carbonic anhydrase model complexes

2019 ◽  
Vol 6 (8) ◽  
pp. 190407 ◽  
Author(s):  
DongKook Park ◽  
Man Sig Lee
Keyword(s):  
Transition Metals ◽  
Carbonic Anhydrase ◽  
Kinetic Study ◽  
Water Ligand ◽  
Stopped Flow ◽  
Rapid Rise ◽  
Ph Titration ◽  
Model Complexes ◽  
Hydration Rate ◽  
Biomimetic Complexes

The rapid rise of the CO 2 level in the atmosphere has spurred the development of CO 2 capture methods such as the use of biomimetic complexes that mimic carbonic anhydrase. In this study, model complexes with tris(2-pyridylmethyl)amine (TPA) were synthesized using various transition metals (Zn 2+ , Cu 2+ and Ni 2+ ) to control the intrinsic proton-donating ability. The pK a of the water coordinated to the metal, which indicates its proton-donating ability, was determined by potentiometric pH titration and found to increase in the order [(TPA)Cu(OH 2 )] 2+ < [(TPA)Ni(OH 2 )] 2+ < [(TPA)Zn(OH 2 )] 2+ . The effect of pK a on the CO 2 hydration rate was investigated by stopped-flow spectrophotometry. Because the water ligand in [(TPA)Zn(OH 2 )] 2+ had the highest pK a , it would be more difficult to deprotonate it than those coordinated to Cu 2+ and Ni 2+ . It was, therefore, expected that the complex would have the slowest rate for the reaction of the deprotonated water with CO 2 to form bicarbonate. However, it was confirmed that [(TPA)Zn(OH 2 )] 2+ had the fastest CO 2 hydration rate because the substitution of bicarbonate with water (bicarbonate release) occurred easily.

scholarly journals KINETIC STUDY ON ANIONIC σ-COMPLEX FORMATION BETWEEN 2,4,6-TRINITROANISOLE AND METHOXIDE ION BY HIGH PRESSURE STOPPED-FLOW METHOD

1979 ◽  
Vol 8 (6) ◽  
pp. 671-674 ◽  
Author(s):  
Noboru Takisawa ◽  
Muneo Sasaki ◽  
Fujitsugu Amita ◽  
Jiro Osugi
Keyword(s):  
High Pressure ◽  
Complex Formation ◽  
Kinetic Study ◽  
Stopped Flow ◽  
Flow Method ◽  
Methoxide Ion

Mechanism of bromination of a quaternary pyrimidinium cation. Change of rate determining step with acidity

1978 ◽  
Vol 56 (23) ◽  
pp. 2970-2976 ◽  
Author(s):  
Oswald S. Tee ◽  
David C. Thackray ◽  
Charles G. Berks
Keyword(s):  
Kinetic Study ◽  
Rate Constants ◽  
Aqueous Media ◽  
Stopped Flow ◽  
Flow Method ◽  
High Acidity ◽  
Rate Determining Step ◽  
Kinetics Of ◽  
Good Agreement

The kinetics of bromination of the 1,2-dihydro-1,3-dimethyl-2-oxopyrimidinium cation (Q+) in aqueous media (pH 0–5) have been studied using the stopped-flow method. At the higher acidities (pH < 2) the results are consistent with rate determining attack by bromine upon the pseudobase (QOH), whereas at low acidities (pH > 4) it appears that pseudobase formation is rate determining. The change occurs because at high acidity the reversal of the pseudobase QOH to the cation is fast relative to bromine attack, whereas at low acidity the converse is true. Results obtained at intermediate acidities (pH 2–4) are consistent with this interpretation.A separate kinetic study of pseudobase formation (and decomposition) yielded rate constants in good agreement with those derived from the bromination study.

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