Letters to the editor: Correlation of conformation and biological activity in lysozyme "loop" homologs

Ten synthetic homologs of the loop region of lysozyme (residues 64 to 82), in which one or two ammo acid residues were replaced by alanine, have been prepared, and their antigenic reactivity was assessed by their capacity to bind to anti-loop antibodies. The results of these binding activities were compared with the computed changes in probability of β-bend occurrence, based on statistical analysis relating the conformation to amino acid sequence. For most of the peptides tested the antigenic activity correlated well with the relative probability of β-bend formation. The activities were lower than the predicted values when the substitution with alanine caused also a disruption of a hydrogen bond.It thus appears that both the β-bend structural feature and hydrogen bonding are involved in the antigenic activity of the conformation-dependent lysozyme loop.