Evidence of the association of biopolymers by nmr-measurements using magnetic isotope effects

By means of the spin-echo technique the transverse relaxation times of water protons are determined for protein (horse-radish peroxidase, human serum albumin) and DNA solutions in dependence on the biopolymer concentration (>= 1%). From the results at high concentrations association effects are deduced. The evidence of an interaction between the protein molecules was made possible only by using magnetic isotope effects which reduce the magnetic dipole-dipole interactions within and between the water molecules. (author)