Conformation of dehydropeptides: synthesis and solution structure of model peptides containing (E) and (Z) dehydroaminobutyric acid residues

Chauhan, V. S. ; Gupta, Alka (1993) Conformation of dehydropeptides: synthesis and solution structure of model peptides containing (E) and (Z) dehydroaminobutyric acid residues International journal of peptide and protein research, 41 (5). pp. 421-426. ISSN 0367-8377

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Official URL: http://onlinelibrary.wiley.com/doi/10.1111/j.1399-...

Related URL: http://dx.doi.org/10.1111/j.1399-3011.1993.tb00460.x

Abstract

Six model dipeptide methyl amides containing dehydroaminobutyric acid (Δ Abu) of the type Boc-X-δzAbu-NHCH3 and Box-X-δε Abu-NHCH3, X = Ala, Val, Phe (Boc = tert-butoxycarbonyl), have been synthesized and their solution conformations explored using 300 MHz 1H NMR and IR spectroscopy. Studies based on delineation of intramolecularly hydrogen bonded NH groups in CDCl3 and (CD3)2SO revealed that none of the NH groups is appreciably solvent shielded. Difference NOE (Nuclear Overhauser Effect) studies have also failed to detect the presence of any discernible turn structure in these peptides. These studies indicate that the conformational preferences of peptides containing, α, β-dehydroaminobutyric acid are different from those of ΔZPhe and ΔZLeu. It appears that steric interactions due to the β-substituent in the dehydroamino acid moiety play an important role. Unlike ΔZPhe and ΔZLeu, which have relatively large β-substituents, phenyl and isopropyl, respectively, and stabilize a β-turn, the β-methyl group of ΔZAbu or Δε Abu is readily accommodated in extended conformation. Clearly, the size of β-substituent in dehydroamino acid crucially influences the conformational preferences. Thus, it may be possible to use different dehydroamino acids to introduce variable but definite constraints in synthetic peptides.

Item Type:Article
Source:Copyright of this article belongs to Munksgaard International Publishers.
Keywords:Constrained Peptides; Dehydroamino Acids; NMR; Solution Conformation
ID Code:8227
Deposited On:26 Oct 2010 12:08
Last Modified:30 May 2011 11:31

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