The crystal structure of Afc-containing peptides.
A systematic structural analysis of Afc (9-amino-fluorene-9-carboxylic acid) containing peptides is here reported. The crystal structures of four fully protected tripeptides containing the Afc residue in position 2: Z-X(1)-Afc(2)-Y(3)-OMe (peptide a: X = Y = Gly; peptide b: X = Aib, C(alpha, alpha)-dimethylglycine, Y = Gly; peptide c: X = Gly, Y = Aib; peptide d: X = Y = Aib) have been solved by x-ray crystallography. All the results suggest that the Afc residue has a high propensity to assume an extended conformation. In fact, the Afc residue adopts an extended conformation in three peptides examined in this paper (peptides a-c). In contrast, Afc was found in a folded conformation, in the 3(10)-helical region, only in the peptide d, in which it is both preceded and followed by the strong helix promoting Aib.
Lombardi
A
A
Centro Interuniversitario di Ricerca su Peptidi Bioattivi, CNR, University of Napoli "Federico II" via Mezzocannone 4, I-80134 Napoli, Italy.
De Simone
G
G
Galdiero
S
S
Nastri
F
F
Di Costanzo
L
L
Makihira
K
K
Yamada
T
T
Pavone
V
V
D000596:Amino Acids / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005449:Fluorenes / Q000737:chemistry*; D005998:Glycine / Q000737:chemistry; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D011487:Protein Conformation
C119175:9-amino-9-fluorenecarboxylic acid; D000596:Amino Acids; D005449:Fluorenes; D009842:Oligopeptides; D005998:Glycine