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An application of 1 H nuclear magnetic resonance to the determination of hydrophobic interactions in peptides
Author(s) -
Kumar N. G.,
Roeske R. W.
Publication year - 1978
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270110606
Subject(s) - chemistry , tryptophan , stereochemistry , peptide , phenylalanine , resonance (particle physics) , isopropyl , proton nmr , valine , amino acid , crystallography , organic chemistry , biochemistry , physics , particle physics
Intermolecular hydrophobic interactions between the indole or phenyl moieties of the peptides containing L ‐tryptophan ( L ‐Trp) or L ‐phenylalanine ( L ‐Phe) residues and the apolar isopropyl groups of the peptides containing L ‐leucine ( L ‐Leu) or L ‐valine ( L ‐Val) in aqueous solutions have been detected by 1 H NMR by monitoring the observed changes in the proton magnetic resonance parameters of the methyl resonances of the peptides containing L ‐Leu or L ‐Val residues. The 1 H NMR data indicate that intermolecular hydrophobic interactions are responsible for the observed changes in the proton magnetic resonance parameters of the methyl resonances. For example, when a solution of glycylglycylleucine (Gly‐Gly‐ L ‐Leu) in deuterium oxide was mixed with glycylglycyltryptophan (Gly‐Gly‐ L ‐Trp), the methyl protons of Gly‐Gly‐ L ‐Leu exhibited large diamagnetic ring current shifts. However, when glycylglycylglycine (Gly‐Gly‐Gly) was substituted for Gly‐Gly‐ L ‐Trp in the NMR experiment, the methyl resonances did not show any upfield or downfield shift, thereby demonstrating that the observed upfield shifts are not due to bulk susceptibility differences between solutions. The C‐terminus peptides containing L ‐Leu or L ‐Val residues bind to the aromatic L ‐Trp or L ‐Phe peptides better than the N‐terminus L ‐Leu or L ‐Val peptides. The C‐terminus Gly‐Gly‐ L ‐Leu binds better than the C‐terminus glycylglycylvaline (Gly‐Gly‐ L ‐Val). The strength and specificity of hydrophobic interactions in several small peptides are discussed.