| Conformational variability of Gly-Gly segments in peptides: A comparison of the crystal structures of an acyclic pentapeptide and an octapeptide (1997) | |||||||||
Abstract | |||||||||
| The crystal structure of an acyclic pentapeptide, Boc-Gly-Gly-Leu-Aib-Val-OMe, reveals an extended conformation for the Gly-Gly segment, in contrast to the helical conformation determined earlier in the octapeptide Boc-Leu-Aib-Val-Gly-Gly-Leu-Aib-Val-OMe [I. L. Karle, A. Banerjee, S. Bhattacharjya, and P. Balaram [1996] Biopolymers, Vol. 38, pp. 515-526). The pentapeptide crystallizes in space group P21 with one molecule in the asymmetric unit. The cell parameters are: a = 10.979(2) Å, b = 9.625(2) Å, c = 14.141(2) Å, and = 96.93(1)°, R = 6.7% for 2501 reflections (I > 3 (I)). The Gly-Gly segment is extended ( 1 = -92°, 1 = -133°, 2 = 140°, 2 = 170°), while the Leu-Aib segment adopts a type II -turn conformation ( 3 = -61°, 3 = 130°, 4 = 71°, 4 = 6°). The observed conformation for the pentapeptide permits rationalization of a structural transition observed for the octapeptide in solution. An analysis of Gly-Gly segments in peptide crystal structures shows a preference for either -turn or extended conformations. | |||||||||
Publication details | |||||||||
| |||||||||