Effects of amino acids and chirality for molecular folding of desoxaroline-ascidiacyclamide derivatives: X-ray crystal structures of four cyclic octapeptides including unusual amino acids, cyclo(-Ile-aThr-D-Val-Thz-)(2), cyclo(-Ala-aThr-D-Val-Thz-Ile-aThr-D-Val-Thz-), cyclo(-Val-aThr-D-Val-Thz-Ile-aThr-D-Val-Thz-), and cyclo(-Ile-aThr-Val-Thz-Ile-aThr-D-Val-Thz-)

Citation
A. Asano et al., Effects of amino acids and chirality for molecular folding of desoxaroline-ascidiacyclamide derivatives: X-ray crystal structures of four cyclic octapeptides including unusual amino acids, cyclo(-Ile-aThr-D-Val-Thz-)(2), cyclo(-Ala-aThr-D-Val-Thz-Ile-aThr-D-Val-Thz-), cyclo(-Val-aThr-D-Val-Thz-Ile-aThr-D-Val-Thz-), and cyclo(-Ile-aThr-Val-Thz-Ile-aThr-D-Val-Thz-), BIOPOLYMERS, 58(3), 2001, pp. 295-304
Citations number
30
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOPOLYMERS
ISSN journal
0006-3525 → ACNP
Volume
58
Issue
3
Year of publication
2001
Pages
295 - 304
Database
ISI
SICI code
0006-3525(200103)58:3<295:EOAAAC>2.0.ZU;2-Z
Abstract
Desoxazoline derivative of ascidiacyclamide (I), cyclo(-L-lle-L-allo-threon ine-D-Val-thiazole-)(2), was modified to disturb the C-2-symmetry. An Ile(1 ) residue of 1 was replaced for Ala (2) or Val (3), and the D-Val(3) residu e was replaced for Val (4). The crystal structures of 1-4 were analyzed by x-ray diffraction methods. The molecules of all compounds were folded and t his type of structure was not observed in x-ray structures of ascidiacyclam ide derivatives so far except for patellamide D. The folding patterns of 1- 4 were similar to each other and resembled that of patellamide. The asymmet ric modifications at position I caused the conformational changes at local area, and these were related with the peptide-peptide and peptide-solvent i nteractions. Despite the diverse backbone conformation by the epimeric modi fication at position 3, the entire molecule of 4 was folded. These results mean that (1) the desoxazoline-ascidiacyclamides favored the folded structu res and (2) the modifications of the side chain size at position I and the chirality at position 3 brought the local conformational changes to derivat ives, suggesting: that (3) the lack of the oxazoline block leads to conform ational flexibility of 1-4, which accepts the conformational change with no drastic change on the entire structure. (C) 2001 John Wiley & Sons, Inc.