| Autor: |
Järv, Jaak, Kesvatera, Tônu, AAviksaar, Aavo |
| Předmět: |
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| Zdroj: |
European Journal of Biochemistry; Aug76 Part 2, Vol. 67 Issue 2, p315-322, 8p |
| Abstrakt: |
The Michaelis-Menten parameters kcat, Ks(app) and the second-order rate constants kII = k2/Ks of acetylcholinesterase-catalyzed hydrolysis of 25 acetic esters with non-ionic leaving groups have been determined at 25°C and pH 7.5 in 0.15 M KC1. A linear relationship between the substrate non-covalent binding capacity and the leaving group hydrophobicity, and a multiparameter correlation of the acetylation reaction rate constant logarithm with the leaving group inductive effect, hydrophobicity, and steric effect, have been established. The acetyl-enzyme deacetylation rate constant has been calculated. Taken together, a fairly complete understanding of acetylcholinesterase specificity is possible. The data are consistent with a model of the acetylcholinesterase active site, in which the catalytically active groups are located at the bottom of a jaws-like slit with a limited range of hydrophobic walls that provide the sorption of the substrate leaving groups not longer than that in n-butyl acetate. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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