Study of the Denaturation Process in Albumin−Urea Solutions by Means of the Thermally Stimulated Depolarization Currents Technique

Abstract

The dielectric relaxation of bovine serum albumin (BSA) aqueous solution was studied in various stages of urea denaturation by means of the thermally stimulated depolarization currents (TSDC) technique. A large variation of urea concentration was utilized (0-4 M). Special attention was given for concentrations between 0.006 and 0.050 M, which are comparable to those measured in normal and uremic human serum. The TSDC spectrum consists of two main bands in the temperature range 100-300 K: (1) a broad low-temperature band (A) with two maxima at about 128 and 142 K, which are attributed to the (re)orientation mechanisms of bulk and hydration water molecules, respectively, and (2) an intense band (B), whose position varies in the range between 230 and 245 K and which is attributed to the (re)orientation of protein macromolecules. Two peaks of lower intensity (B 1 and B 2 ) are resolved in the rising part of band B and are most likely due to relaxation mechanisms of the side chains of BSA. The activation energies for the last three mechanisms depend on urea concentration, and this fact might be attributed to the conformational changes of BSA upon denaturation. It is of interest to note that the macromolecules' activation energies depend drastically on the concentration of urea up to 0.05 M. Abstract published in AdVance ACS Abstracts, December 15, 1995.

TSDC spectroscopy of relaxational and interfacial phenomena

“…Vassilikou-Dova et al [385] studied the dielectric relaxation of bovine serum albumin (BSA) in aqueous solution with various stages of urea denaturation by the TSDC technique. A large variation of urea concentration was utilized (0-4 M).…”

Study of the Dynamic Structure of Native and Hydrophobized Glucose Oxidase by Time-Domain Dielectric Spectroscopy

“…It has been used for the study of myoglobin, lysozyme, RNase, and Binase. [19][20][21][22][23][24][25][26][27][28][29][30][31][32] In this work, we compare the dynamic behaviors of native and hydrophobized GOx by the TDDS method, and we evaluate the effect of the attachment of hydrophobic groups to the protein molecule on its structure.…”

“…It has been shown that the application of time-domain dielectric spectroscopy (TDDS) has been successful in obtaining new information on the structural and dynamic parameters of protein globules in conformational transitions induced by temperature and pH changes. It has been used for the study of myoglobin, lysozyme, RNase, and Binase. − …”