Linear oligopeptides. 188.Crystallographic characterization of the conformation of the 1-aminocyclopentane-1-carboxylic acid residue in simple derivatives

Abstract

GIOVANNI VALLE, MARCO CRISMA, and CLAUDIO TONIOLO. Can. J. Chem. 66, 2575Chem. 66, (1988. The crystal structures of six derivatives of the Cm."-dialkylated a-aminoacid residue 1-aminocyclopentane-1-carboxylic acid (Acc5) have been determined. These are Z-AccS-OH, Z-Acc5-OH acetone hemi-solvate, Fmoc-Acc5-OH, m C l~c -~c c~-O H , p~r~z -~c c 5 -O~, and the 5(4H)-oxazolone from p~r~z -~c c s -O~. The values determined for the torsion angles about the N-Ca (4) and Ca-CO ($1 bonds correspond to folded, potentially a/310-helical conformations for the AccS residue of Z-AccS-OH, Z-AccS-OH acetone hemi-solvate, mC1Ac-Acc -OH, and p~r~z -~c c 5 -~~. The structure of F~O C -A C C~-O H , however, is unusual in having a semi-extended conformation for the 4 , I) angles, accompanied by a cis arrangement of the amide group of the secondary urethane moiety. The dependence of the N-Cm-C' bond angle on the I) torsion angle and the asymmetry at the Ca atom are relevant features of the Acc5 residues. The position of the cyclopentyl ring relative to the peptide chain and its puckering parameters for the six compounds are also discussed.GIOVANNI VALLE, MARCO CRISMA et CLAUDIO TONIOLO. Can. J. Chem. 66,2575Chem. 66, (1988. On a dCterminC les structures cristallines de six dCrivCs Ca~a-dialkylCs du rCsidu d'acide a-aminC, amino-1 cyclopentanecarboxylique-1 (Acc5). I1 s'agit du Z-Acc5-OH, du Z-AccS-OH hCmisolvatC par 17acCtone, du ~moc-Acc5-OH, du mC1Ac-AccS-OH, du p~r~z -~c c S -O~ et de la (4H)-oxazolone-5 prkparte a partir du p~r~z-AccS-OH. Les valeurs qui ont Ct C obtenues pour les angles de torsion autour des liaisons N-Ca (4) et Ca-CO (I)) du rCsidu AccS du Z-AccS-OH, du Z-AccS-OH hCmisolvatC par l'acCtone, du mC1Ac-Acc5-OH et du pBrBz-Accs-OH correspondent a des conformations repliCes qui sont possiblement a/310-hClicoldales. Toutefois, la structure du Fmoc-Acc5-OH est inhabituelle; sur la base des angles 4 et I) elle posskde une conformation semi-Ctendue qui est accompagnte par un arrangement cis du groupement amide de la portion secondaire de l1urCthane. Le fait que l'angle de la liaison N-Ca-C' varie en fonction de I'angle de torsion I) et de I'asymCtrie du Ca et sont caractCristiques importantes des rCsidus Acc5. On discute aussi de la position du cyclopentane par rapport i la chahe peptidique ainsi que des paramktres de plissement des six composCs.[Traduit par la revue]

Stereochemical Control of Peptide Folding

“…77 Crystal structure determinations of short Ac 6 c containing peptides quickly con®rmed this expectation. 77±79 Helical conformations were also demonstrated in structure determinations involving Ac 5 c, 80,81 and Ac 7 c 82 peptides. The Ac n c residues appear predominantly to be limited to helical conformations.…”

Preparation and Structure ofβ-Peptides Consisting of Geminally Disubstitutedβ2,2- andβ3,3-Amino Acids: A Turn Motif forβ-Peptides

“…81 (1998) 2224 20 ) Coupling reactions were monitored using 2,4,6-trinitrobenzenesulfonic acid (TNBS) [43]. 21 ) In almost all crystal structures containing the a-analogues of 16c [44] and 16d [45], the amino group occupies the axial position [46]. a ) For specification of the asterixed compound numbers, see Formula 2, and 10 ± 13 above.…”

Structures of peptides from α‐amino acids methylated at the α‐carbon,

“…5 ( 4~) -oxazolones, [13][14][15][16][17] carboxylic acid chlorides1' and azides, '' and N-carboxyanhydrides") of common use in peptide synthesis. 4.…”