THEORETICAL STUDIES OF PROTIUM DEUTERIUM FRACTIONATION FACTORS AND COOPERATIVE HYDROGEN BONDING IN PEPTIDES

摘要

We have calculated fractionation factors (phi) for a water cluster and a wide range of peptide clusters. We find that low fractionation factors can occur when both charged interactions and cooperative hydrogen-bonded networks are present. Correlations between fractionation factors and hydrogen-bonded N-O distances or N-H bond lengths have been found which are nonlinear and show maximum values of fractionation factors at N-O distances of about 2.80 Angstrom. These calculations support the wide range (0.28-1.47) of fractionation factors found in proteins [Loh, S. N.; Markley, J. L. Biochemistry 1994, 33, 1029-1036]. [References: 34]