ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The crystal structures of the isovaline (Iva) containing dipeptides, Boc-D-Iva-L-Pro-OBzl and Boc-L-Iva-L-Pro-OBzl, were determined by x-ray diffraction. The diastereomeric peptides were shown to adopt unturned conformations closely similar to each other (φIva 52°, ψIva 46°, φPro-65°, and ψPro 143° for D-Iva-L-Pro sequence and φIva 52°, ψIva 44°, φPro -63°, and ψpro 148° for L-Iva-L-Pro sequence). The Pro ring of each peptide was in Cγ-endo conformation. The unusually large ∠CIva-NPro-CδPro values (131° in both peptides) were observed, that was due to steric repulsion between the δ-methylene of Pro and the alkyl side chain of Iva residue. These conformations were essentially the same as that of the corresponding α-aminoisobutyric acid (Aib)-containing peptide Boc-Aib-L-Pro-OBzl. The result has demonstrated that replacement of either one of the two methyl groups of the Aib residue in Boc-Aib-L-Pro-OBzl with an ethyl group does not cause any significant change in the unturned conformation of the dipeptide. © 1993 John Wiley & Sons, Inc.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360330807
Permalink
