The Dielectric Investigation of Polypeptides. I. The Dielectric Increments of Amino Acid Polypeptides

Conner, W. P.; Clarke, Rosalind; Smyth, Charles P.

doi:10.1021/ja01258a042

Cited by 13 publications

(3 citation statements)

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“…(4) The diacetyllecithin has a specific volume of 0.9 and a molecular weight of 377.26 (5) The high-frequency value of the dielectric constant for pure phospholipid is 2.0.27…”

Section: Discussionmentioning

confidence: 99%

Dielectric characterization of lecithins in media of differing dielectric constants

Pennock¹,

Goldman²,

Chacko³

et al. 1973

J. Phys. Chem.

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The dielectric constant and conductivity of lecithin and diacetyllecithin solutions were determined at several concentrations in solvents of differing dielectric constant and at frequencies from 0.5 to 250 MHz. These data were shown to fit the general formula e* = e " + (eo -)/{l + [/(///c)]1_"i> where e* is the complex dielectric constant, eo and are the lowand high-frequency dielectric constants, f is the frequency, fc is a generalized characteristic frequency, and a is a constant, 0 < a < 1. A linear dependence of the low-frequency dielectric constant on concentration was also found. These two results permitted a complete description of the data in terms of characteristic frequency and dielectric increment which are indices of molecular size and dipole length. The values for these parameters were consistent with the known structure of lecithin in high dielectric constant media (e > 30). However, the dielectric increment was found to decrease with decreasing solvent dielectric constant. This is interpreted as an increase in dipole-dipole interaction to produce small molecular aggregates.

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“…(4) The diacetyllecithin has a specific volume of 0.9 and a molecular weight of 377.26 (5) The high-frequency value of the dielectric constant for pure phospholipid is 2.0.27…”

Section: Discussionmentioning

confidence: 99%

Dielectric characterization of lecithins in media of differing dielectric constants

Pennock¹,

Goldman²,

Chacko³

et al. 1973

J. Phys. Chem.

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“…Furthermore, some sources of error besides those involved in the experimental determination of the rate must be considered. For example, a discrepancy of 5 per cent with regard to the value of the dielectric constant given for dioxane by t?kkerlSf and Short (2) has been reported more recently (9). Another error may result from the assumption that the medium is homogeneous.…”

Section: Calculation Of the Thermic And Coulombic Energies Of Activationmentioning

confidence: 95%

The Influence of the Medium Dielectric Strength Upon Trypsin Kinetics

Castañeda-Agulló

Castillo

1959

The Journal of General Physiology

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The use of aqueous alkali for the titration of esterolytic activity when the esters are dissolved in alcoholic solutions, results in an error due to changes in the ionization of the buffer. This is corrected by titrating with alkali in the same solvent as the substrate.Alcohols and other substances which change the dielectric strength of water modify the rate of hydrolysis of BAEE 1 and TSAME by trypsin to an extent proportionate to their effect on the dielectric strength. The reaction rate increases with diminished dielectric strength and v/ce rersa. At low concentrations of substance there seems to be no specific effect other than that derived of the variation in dielectric strength. At higher concentrations, the enzyme might be denatured. In addition, it is probable that specific effects of each substance might intervene. The Coulombic and thermic energies of activation were calculated for the two esters in various solvents. The plot of the logarithm of rate constant rs. reciprocal of dielectric constant yields a straight line with positive slope. This behavior is similar to that of a non-enzymatic positive ion-dipole reaction. Trypsin reacts like a positive ion. The possible influence of the dielectric strength on the regulation of the equilibria involved in the interconversion of the various forms of trypsin in solution (active, inactive, denatured) is discussed. INTRODUCTIONSchwert and Eisenberg (19) hydrolyzed BAME and BAEE in different alcohols at various concentrations with the hope that by varying the solvent it might be possible to differentiate the two supposed steps of the enzymatic reaction (formation and activation of Michaelis complex). Although these investigators did not realize their objective, they did find that hydrolyses of these esters failed to follow zero order kinetics in the presence of alcohols. These solvents gave rise to an increase in the initial rate of hydrolysis to an extent i Throughout this paper the following abbreviations will be used: BAEE, benzoyl-T.-arginine ethyl ester. TSAME, p-toluenesulfonyl-T.-arginine methyl ester. BTEE, benzoyl-~tyrosine ethyl ester. BAME, benzoyl-~arginine methyl ester. ATEE, acetyl-L-tyrosine ethyl ester. 617

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“…Measurements of the dielectric constant of aqueous solutions of biuret (95) and of the dielectric increment1 of biuret are on record (73). Data are also available concerning its electrocapillary function (164), its piezoelectric behavior (186), and the magnetic susceptibility of its carbonyl group (282).…”

Section: Nh-mentioning

confidence: 99%

Biuret And Related Compounds

Kurzer¹

1956

Chem. Rev.

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The Dielectric Investigation of Polypeptides. I. The Dielectric Increments of Amino Acid Polypeptides

Cited by 13 publications

References 0 publications

Dielectric characterization of lecithins in media of differing dielectric constants

Dielectric characterization of lecithins in media of differing dielectric constants

The Influence of the Medium Dielectric Strength Upon Trypsin Kinetics

Biuret And Related Compounds

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