Effect of the Medium Dielectric Strength on the Activity of Alpha Chymotrypsin
Open Access
- 1 September 1959
- journal article
- Published by Rockefeller University Press in The Journal of general physiology
- Vol. 43 (1), 127-137
- https://doi.org/10.1085/jgp.43.1.127
Abstract
The rates of hydrolysis of TrEE, TEE, and ATEE1 by α-chymotrypsin were determined in media of variable dielectric strength. Many substances which modify the dielectric constant of the medium, exert additional specific effects on the reaction rate, noticeable at more or less elevated concentrations. Notwithstanding, it is possible to differentiate the dielectric and specific effects by comparing the rates in solvents of distinct nature at relatively low concentrations. Thus, the effect of varying the dielectric strength could be studied within wider ranges (ΔD = 20 with TrEE and ca. 28 with ATEE) than in the previous study of trypsin (ΔD = 12). The dielectric effect on α-chymotrypsin is the opposite of that observed with trypsin. In both cases there is a linear relationship between the logarithm of the rate of hydrolysis and the reciprocal of the dielectric constant. The slope is negative with α-chymotrypsin and positive with trypsin. According to expressions relating the dielectric constant to the rate in non-enzymatic reactions, the behavior of α-chymotrypsin is like that of a negative ion, while trypsin behaves as a positive ion. The enzyme activity appears to depend upon the arrangement of charges in the enzyme and substrate molecules, rather than on the presence of certain atomic groupings in the substrate.Keywords
This publication has 5 references indexed in Scilit:
- THE INFLUENCE OF THE MEDIUM DIELECTRIC STRENGTH UPON TRYPSIN KINETICSThe Journal of general physiology, 1959
- SIMULTANEOUS HYDROLYSES OF ESTERS AND PROTEINS AT SATURATION LEVELSThe Journal of general physiology, 1958
- ELECTROPHORESIS AND SOLUBILITY OF CHYMOTRYPSINOGEN B AND CHYMOTRYPSIN BJournal of Biological Chemistry, 1949
- THE EFFECT OF METHANOL ON THE HYDROLYSIS OF ACETYL-l-TYROSINAMIDE BY CHYMOTRYPSINJournal of Biological Chemistry, 1949
- THE SPECIFIC PEPTIDASE AND ESTERASE ACTIVITIES OF CHYMOTRYPSINJournal of Biological Chemistry, 1949