Structure Analysis and Proton Assignment of Mucin Derivative Peptides with Unnatural Amino Acids on the Backbone by NMR Spectroscopy

Abstract

The purpose of this project was to acquire two-dimensional proton NMR data for two synthesized mutant mucin peptides, make assignments for all the hydrogen atoms on the peptides, and analyze for any unique structure present. Mucin peptides are considered to have potential applications in the area of cancer vaccine according to many studies on their biological activity. Two short mucin peptide derivatives based on the native sequence Gly-Val-Thr-Ser-Ala-Pro-Asp were synthesized with the Pro residue substituted by cyclohexylcarboxylic acid (cyHCA) and 4-aminobenzoate (4-aBz). Two-dimensional proton NMR data were used to make assignments of all the hydrogen atoms on the peptides and to verify that the synthesized peptides contained the intended sequences. Hydrogen atoms on the peptides that are in close spatial proximity were analyzed for unique structural features of the peptides. The NMR data collected for each peptide correlate with the expected data based on the known structure of the mucin peptide.