Polymethylene spacer linked bis(Ala) peptides form modified beta-sheet structures. Crystal structure and self-assembly pattern of adipoyl and suberoyl analogues.

The adipoyl- and suberoyl-linked bis(Ala) peptides have an extended backbone between the two C alpha atoms in each molecule. They self-assemble, through intermolecular hydrogen bonds and stacking of parallel strands, into highly ordered modified beta-sheet-like structures. Crystals data for adipoyl bis(Ala)diester are as follows: C14H24N2O6, monoclinic space group P2(1), a = 4.900(1), b = 29.093(10), c = 6.021(2) A, beta = 104.20(2) degrees, R = 0.053 for 1100 data > 3 sigma (F); for suberoyl bis(Ala)diester: C16H28N2O6, monoclinic space group P2(1), a = 4.887(2), b = 32.650(9), c = 6.004(2) A, beta = 103.79(3), R = 0.070 for 1065 data > 3 sigma (F).