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Conformational effects of C-alpha,C-alpha-dipropargylglycine as a constrained residue

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Title Conformational effects of C-alpha,C-alpha-dipropargylglycine as a constrained residue
 
Creator DAMODHARAN, L
MOHANRAJA, K
KOTHA, S
DURANI, S
PATTABHI, V
 
Subject alpha-aminoisobutyric-acid
peptide conformations
crystal-structure
side-chains
oligopeptides
glycines
c-alpha,c-alpha-dipropargylglycine residue
d-chiral residue
dipeptides
tripeptides
beta-turn
crystal structures
solution structure
 
Description A useful synthon to approach artificial phenylalanyl peptides in a [2 + 2 + 2] cycloaddition reaction, C-alpha,C-alpha-dipropargylglycine (Dprg) is examined for its conformational preferences as a constrained residue. Crystal structure analysis and preliminary NMR results establish possible preference of the residue for folded (alpha) rather than extended (beta) region of the phi,psi conformational space. Boc-Dprg-L-Leu-OMe (1) displays two molecular conformations within the same crystallographic asymmetric unit, with Dprg in the alpha (R) or alpha (L) conformation, participating in a type I beta -turn or an alpha (L)-alpha (R)-type fold, in which Leu(2) assumes the alpha (R) conformation stereochemically favored for an L-chiral residue. Boc-Dprg-D-Val-L-Leu-OMe (2) displays a type I ' beta -turn conformation in crystal, with both Dprg(1) and D-Val(2) assuming the alpha (L) conformation stereochemically favored for a D-chiral residue, with 4 --> 1 type hydrogen bond linking L-Leu(3) NH is with Boc CO. NMR analysis using temperature variation, solvent titration, and a spin probe study suggests a fully soh,ent-exposed nature of Dprg NH, ruling out a fully extended C-5-type conformation for this residue, and soli,ent sequestered nature of L-Leu(3) NH, suggesting possibility of a beta -turn due to Dprg assuming a folded conformation. (C) 2001 , Inc.
 
Publisher JOHN WILEY & SONS INC
 
Date 2011-08-04T12:36:55Z
2011-12-26T12:54:43Z
2011-12-27T05:42:56Z
2011-08-04T12:36:55Z
2011-12-26T12:54:43Z
2011-12-27T05:42:56Z
2001
 
Type Article
 
Identifier BIOPOLYMERS, 59(5), 330-338
0006-3525
http://dx.doi.org/10.1002/1097-0282(20011015)59:5<330::AID-BIP1030>3.3.CO;2-D
http://dspace.library.iitb.ac.in/xmlui/handle/10054/9361
http://hdl.handle.net/10054/9361
 
Language en