A predictive method for determining possible three-dimensional foldings of immunoglobulin backbones around antibody combining sites

A method has been developed to replace segments of a protein backbone by other segments with standard peptide units and given (φ, ψ) angles. Restrictions were imposed by fixed orientations of the N- and C-terminals and by the absence of steric hindrance between non-bonding atoms. This procedure was applied to the prediction of three dimensional backbone conformations of antibody combining sites based on the amino acid sequences of the six complementarity determining regions. In particular, the detailed backbone structure around the combining site of immunoglobulin MOPC-315 was predicted. Atomic co-ordinates of all non-hydrogen backbone atoms including C_β of the predicted structure were given so that future comparisons with experimental data and other predictions could be made.