MICROWAVE DIELECTRIC STUDY ON BOUND WATER OF GLOBULE PROTEINS IN AQUEOUS-SOLUTION

A dielectric relaxation peak due to bound water of globule proteins in aqueous solution was observed at first by the use of a time domain re flectometry. This peak locates around 100 MHz as well as that of the a queous DNA solution and the moist collagen, and has a relaxation stren gth in proportion to surface of the globule protein except for trypsin and pepsin of hydrolase. It is suggested that this peak is caused by orientation of bound water molecules on the protein surface. The numbe r of bound water molecules estimated is in good agreement with that ob tained by other method such as x-ray analysis. The solution exhibits a nother peak below 100 MHz, which is caused by the rotation of globule protein supplemented by migration of the counterion. Its relaxation ti me is completely proportional to the molecular weight of the protein. (C) 1994 John Wiley & Sons, Inc.