Inhibition kinetics of chain-breaking phenolic antioxidants in SDS micelles. Evidence that intermicellar diffusion rates may be rate-limiting for hydrophobic inhibitors such as .alpha.-tocopherol

1986 ◽  
Vol 108 (20) ◽  
pp. 6381-6382 ◽  
Author(s):  
Laurence. Castle ◽  
M. John. Perkins
Keyword(s):  
Alpha Tocopherol ◽  
Phenolic Antioxidants ◽  
Inhibition Kinetics ◽  
Sds Micelles ◽  
Chain Breaking ◽  
Diffusion Rates ◽  
Rate Limiting ◽  
Kinetics Of

Kinetics of the interactions between dyes and micelles

1986 ◽  
Vol 64 (5) ◽  
pp. 955-959 ◽  
Author(s):  
Vincent C. Reinsborough ◽  
Josef F. Holzwarth
Keyword(s):  
Hydrophobic Interactions ◽  
Sodium Dodecylsulfate ◽  
Bulk Solution ◽  
Sds Micelles ◽  
Ph Jump ◽  
Wide Ph Range ◽  
Ph Range ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Continuous Flow Method

The rates of association of three azo dyes, methyl red (MR), methyl orange (MO), and pyridine-2-azo-p-dimethylaniline (PADA), with sodium dodecylsulfate (SDS) and cetyltrimethylammonium bromide (CTAB) micelles in water were measured at 25 °C over a wide pH range by the continuous flow method of integrating observation (CFMIO). The association was considered in 3 steps: bulk solution encounter, pH jump, and electrostatic and hydrophobic interactions. Either the first or third step is rate limiting depending on the charge of the dye. The rate constant of association of neutral PADA, MR, and MO with SDS micelles is approximately 2 × 106 dm3mol−1s−1 while charging the dyes positively increases k to 109 dm3mol−1 s−1. Increasing the hydrophobicity of dye or micelle increases k for the interaction with the neutral dye species. Changes in k with pH for the dye–CTAB association were less pronounced.

SUBSTRATE INHIBITION KINETICS OF MALATHION BIODEGRADATION AND THE EFFECT OF MOLASSES AS COSUBSTRATE

2015 ◽  
Vol 14 (1) ◽  
pp. 109-119 ◽  
Author(s):  
Djaber Tazdait ◽  
Nadia Abdi ◽  
Hakim Lounici ◽  
Nabil Mameri
Keyword(s):  
Substrate Inhibition ◽  
Inhibition Kinetics ◽  
Substrate Inhibition Kinetics ◽  
Kinetics Of

Kinetics of cyclization of S-ethoxycarbonylmethylisothiouronium chloride to 2-imino-4-thiazolidone

1979 ◽  
Vol 44 (3) ◽  
pp. 912-917 ◽  
Author(s):  
Vladimír Macháček ◽  
Said A. El-bahai ◽  
Vojeslav Štěrba
Keyword(s):  
Hydrochloric Acid ◽  
Dilute Hydrochloric Acid ◽  
Base Catalysis ◽  
General Base ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Kinetics Of Formation ◽  
Acid Catalyzed ◽  
Rate Limiting ◽  
Kinetics Of

Kinetics of formation of 2-imino-4-thiazolidone from S-ethoxycarbonylmethylisothiouronium chloride has been studied in aqueous buffers and dilute hydrochloric acid. The reaction is subject to general base catalysis, the β value being 0.65. Its rate limiting step consists in acid-catalyzed splitting off of ethoxide ion from dipolar tetrahedral intermediate. At pH < 2 formation of this intermediate becomes rate-limiting; rate constant of its formation is 2 . 104 s-1.

Kinetics and mechanism of cyclization of N-(2-methoxycarbonylphenyl)-N’-methylsulphonamide to 3-methyl-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide

1991 ◽  
Vol 56 (8) ◽  
pp. 1701-1710 ◽  
Author(s):  
Jaromír Kaválek ◽  
Vladimír Macháček ◽  
Miloš Sedlák ◽  
Vojeslav Štěrba
Keyword(s):  
Potassium Hydroxide ◽  
Acid Catalysis ◽  
Potassium Hydroxide Solution ◽  
Hydroxide Solution ◽  
General Base ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Cyclization Kinetics ◽  
Rate Limiting ◽  
Kinetics Of

The cyclization kinetics of N-(2-methylcarbonylphenyl)-N’-methylsulfonamide (IIb) into 3-methyl-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide (Ib) has been studied in ethanolamine, morpholine, and butylamine buffers and in potassium hydroxide solution. The cyclization is subject to general base and general acid catalysis. The value of the Bronsted coefficient β is about 0.1, which indicates that splitting off of the proton from negatively charged tetrahedral intermediate represents the rate-limiting and thermodynamically favourable step. In the solutions of potassium hydroxide the cyclization of dianion of the starting ester IIb probably becomes the rate-limiting step.

Kinetic analysis of mechanism of intestinal Na+-dependent sugar transport

1985 ◽  
Vol 248 (5) ◽  
pp. C498-C509 ◽  
Author(s):  
D. Restrepo ◽  
G. A. Kimmich
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Sugar Transport ◽  
Enzyme Kinetic ◽  
Steady State Distribution ◽  
State Distribution ◽  
Least Squares Fit ◽  
Coupling Stoichiometry ◽  
Rate Limiting ◽  
Kinetics Of

Zero-trans kinetics of Na+-sugar cotransport were investigated. Sugar influx was measured at various sodium and sugar concentrations in K+-loaded cells treated with rotenone and valinomycin. Sugar influx follows Michaelis-Menten kinetics as a function of sugar concentration but not as a function of Na+ concentration. Nine models with 1:1 or 2:1 sodium:sugar stoichiometry were considered. The flux equations for these models were solved assuming steady-state distribution of carrier forms and that translocation across the membrane is rate limiting. Classical enzyme kinetic methods and a least-squares fit of flux equations to the experimental data were used to assess the fit of the different models. Four models can be discarded on this basis. Of the remaining models, we discard two on the basis of the trans sodium dependence and the coupling stoichiometry [G. A. Kimmich and J. Randles, Am. J. Physiol. 247 (Cell Physiol. 16): C74-C82, 1984]. The remaining models are terter ordered mechanisms with sodium debinding first at the trans side. If transfer across the membrane is rate limiting, the binding order can be determined to be sodium:sugar:sodium.

scholarly journals Effects of Phenylalanine Substitutions in Gramicidin A on the Kinetics of Channel Formation in Vesicles and Channel Structure in SDS Micelles

2005 ◽  
Vol 88 (1) ◽  
pp. 224-234 ◽  
Author(s):  
J.B. Jordan ◽  
P.L. Easton ◽  
J.F. Hinton
Keyword(s):  
Channel Structure ◽  
Gramicidin A ◽  
Channel Formation ◽  
Sds Micelles ◽  
Kinetics Of
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