Conformational behaviour of Cα,α-diphenylglycine: folded vs. extended structures in DϕG-containing tripeptides

✍ Scribed by Vincenzo Pavone; Angela Lombardi; Michele Saviano; Flavia Nastri; Laura Zaccaro; Ornella Maglio; Carlo Pedone; Yuichiro Omote; Yoshinori Yamanaka; Takashi Yamada

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 251 KB
• Volume: 4
• Category: Article
• ISSN: 1075-2617
• DOI: 10.1002/(sici)1099-1387(199802)4:1<21::aid-psc125>3.0.co;2-a

✦ Synopsis

The crystal structures of three fully protected tripeptides containing the Dfg residue (C a,adiphenylglycine) in the central position are reported, namely Z-Gly-Dfg-Gly-OMe (a), Z-Gly-Dfg-Aib-OMe (b) and Z-Aib-Dfg-Aib-OMe (c). The molecular conformations are quite unusual because the Dfg residue adopts a folded conformation in the 3 10 -helical region when the following residue adopts a folded conformation of opposite handedness (peptides b and c). In contrast, the Dfg residue adopts the more frequently observed fully extended conformation when the following residue adopts a semi-extended conformation (peptide a). These findings are in agreement with the theoretical calculations on Ac-Dfg-Aib-NHCH 3 and Ac-Aib-Dfg-NHCH 3 also reported in this work.