A THEORETICAL STUDY OF THE STRUCTURES OF (GLY-PRO-LEU)n AND (GLY-LEU-PRO)n

Theoretical conformation studies have been carried out for the polytripeptides (Gly‐Pro‐Leu)n and (Gly‐Leu‐Pro)n and the Fourier transforms of the structures have been calculated. X‐ray powder patterns of these polymers had indicated that both these polymers take up coiled‐coil triple‐helical structures, but in the case of (Gly‐Pro‐Leu)n it was not clear whether the triple helix is formed by three parallel polypeptide chains or by a single chain folding back on itself (Scatturin et al 1975). Our studies show that both the polytripeptides can take up stereochemically satisfactory triple‐helical structures with three parallel chains. There is also very good agreement between the calculated intensity distribution and that of the observed X‐ray pattern, in each case.