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The effect of N‐methylation on helical peptides
Author(s) -
Chang ChiFon,
Zehfus Micheal H.
Publication year - 1996
Publication title -
peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/(sici)1097-0282(1996)40:6<609::aid-bip2>3.0.co;2-#
Subject(s) - chemistry , methylation , stereochemistry , biochemistry , dna
Abstract In N‐methyl amino acids, the hydrogen of the N‐H group is replaced with a bulky methyl group. While this change is expected to destabilize helical structures, the amount of destabilization is not known. Here the N‐methyl group is placed into several positions of the helical peptides, acetyl‐WGG(EAAAR) 4 A‐amide and acetyl‐WGG(RAAAA) 4 R‐amide, and the melting of the peptides followed using CD. When analyzed using a simple two‐state model, the destabilization associated with the H to CH 3 substitution at 0°C is between 0.3 to 1.7 kcal/mole and is position dependent. The melting data may also be analyzed using a modified form of the Lifson‐Roig statistics that should more correctly model the helix‐coil transition in this small peptide. This analysis fails, however, apparently because the destabilization energy is greater than the energy that can be attributed to a single residue in this model. © 1997 John Wiley & Sons, Inc. Biopoly 40: 609–616, 1996