Conformational studies of ¦Ã-turn in pseudopeptides containing ¦Á-amino acid and conformationally constrained meta amino benzoic acid/meta nitro aniline

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• 作者：Anita Dutt Konar ; ^{anita@iiserb.ac.in}
• 关键词：mABA ; m-amino benzoic acid ; mNA ; m-nitro aniline ; Boc ; tertiary butyloxy carbonyl ; OMe ; methoxy carbonyl ; DCC ; dicyclohexylcarbodiimide ; HOBt ; 1-hydroxy benzotriazole
• 刊名：Journal of Molecular Structure
• 出版年：2013
• 出版时间：27 March, 2013
• 年：2013
• 卷：1036
• 期：Complete
• 页码：350-360
• 全文大小：1573 K

文摘

Reverse turns (commonly ¦Â-turns and ¦Ã-turns), a common motif in proteins and peptides, have attracted attention due to their relevance in a wide variety of biological processes. In an attempt to artificially imitate and stabilize these turns in short acyclic peptides, a series of N-terminally protected pseudopeptides comprising of an ¦Á-amino acid and conformationally constrained meta amino benzoic acid (mABA)/meta nitro aniline (mNA) (peptides I-VI) have been synthesized. The molecules were well characterized by various spectroscopic techniques and subjected to a systematic conformational analysis. Our experimental results reveal that only pseudopeptides I and II with methyl as the sidechain, tertiary butyloxy carbonyl as the N-terminal protecting group and (mABA)/(mNA) at the C-terminus adopt ¦Ã-turn conformations in solid state as well as in solution. Even slight modification of any of the stated conditions donot support the formation of this ¦Ã-turn architecture in the solid state. Interestingly, the peptides III-V which displays extended conformation in solid state forms ¦Ã-turn structure in solution. Thus this result reflects the importance of co-operative steric interactions amongst various amino acid residues in stabilizing a particular conformation in peptides in different phases (solid and solution). This report may open a new avenue in introducing ¦Ã-turn motifs within the bioactive conformation of selected peptides.