The peptide Boc-Gly-Dpg-Gly-Gly-Dpg-Gly-NHMe (1) has been synthesized to examine the conformational preferences of Dpg residues in the context of a poor helix promoting sequence. Single crystals of 1 were obtained in the space group P2(1)/c with a = 13.716(2) Angstrom, b = 12.960(2) Angstrom, c = 22.266(4) Angstrom, and beta = 98.05(1)degrees; R = 6.3% for 3660 data with \F-0\ > 4 sigma. The molecular conformation in crystals revealed that the Gly(1)-Dpg(2) segment adopts phi, psi values distorted from those expected for an ideal type II' beta-turn (phi(Gly(1)) = +72.0 degrees, psi(Gly(1)) = -166.0 degrees; phi(Dpg(2)) = -54.0 degrees, psi(Dpg(2)) = -46.0 degrees) with an inserted water molecule between Boc-CO and Gly(3)NH. The Gly(3)-Gly(4) segment adopts phi, psi values which lie broadly in the right handed helical region (phi(Gly(3)) = -78.0 degrees, psi(Gly(3)) = -9.0 degrees; phi(Gly(4)) = -80.0 degrees, psi(Gly(4)) = 18.0 degrees). There is a chiral reversal at Dpg(5) which takes up phi, psi values in the left handed helical region. The Dpg(5)-Gly(6) segment closely resembles an ideal type I' beta-turn (phi(Dpg(5)) = +56.0 degrees, psi(Dpg(5)) = +32.0 degrees; phi(Gly(6)) = +85.0 degrees, psi(Gly(6)) = -3.0 degrees). Molecules of both chiral senses are found in the centrosymmetric crystal. The C-terminus forms a hydrated Schellman motif, with water insertion into the potential 6 --> 1 hydrogen bond between Gly(1)CO and Gly(6)NH. NMR studies in CDCl3 suggest substantial retention of the multiple turn conformation observed in crystals. In solution the observed NOEs support local helical conformation at the two Dpg residues.