Kinetic study of denaturation and subsequent reduction of disulfide bonds of lysozyme by the rapid ultrasonic absorption measurement

Publisher Website
Google Scholar
Abstract
A New technique for the rapid measurement of ultrasonic absorption with a sampling interval of 5 msec has been developed and applied to the kinetic study of denaturation and subsequant redution of hen egg‐white lysozyme. The lysozyme is denatured by guanidine hydrochloride (GuHCl) orLiBr, and afetr denaturation by GuHCl, its disulfide bonds are reduced by dithiothreitol (DTT). The ultrasonic adsorption coefficient at 9 MHz increases with denaturation but decreases with reduction. The rate constant of denaturation by GuHCl obtained from the rime variance of ultasonic agrees well with that from uv absorption and optical rotation. The time variance if absorption after GuHCl and Dtt have been simultaneously added exhibits two rate constants. Analysis of the constants as functions of regeant concentrations indicates that the intermediates state between native and reduced states is not necessarily the completely denatured state but depends on the concentartions of GuHCl and DTT.