Influence of secondary structure of polyglycine on some conformational properties

Values of four conformational properties, namely unperturbed dimension [r2]0, dipole moment [mu 2], mean squared optical anisotropy [gamma 2], and molar Kerr constant [mK], have been calculated for polyglycine chains allowing several combinations of the secondary structure with the aim of studying the dependence of these magnitudes on the secondary structure of the chain. Two different approaches to the secondary structure have been used. In the first, chains with all their units in a given conformation (random coil, alpha-helix or beta-sheet) are interrupted at several positions by one unit in a different conformation. In the second, chains with varying composition of two conformations alpha-helix/beta-sheet and beta-sheet/random coil were allowed and the results obtained compared with previous work for alpha-helix/random coil chains.