Backbone NMR assignments of recombinant glucagon at pH 6.0

Abstract

The peptide hormone glucagon has served as both a biopharmaceutical agent for clinical use and a model peptide forming amyloid fibrils. As we recently established a recombinant production of glucagon, its backbone NMR assignments at neutral pHs were conducted in the present study. However, as the NMR spectra showed severe line broadening and poor dispersion at pHs 7.5 and 7.0, complete backbone NMR assignments could be obtained at pH 6.0. Interestingly, CSI and TALOS predictions using the assigned chemical shift values indicated different probabilities of secondary structure. These results suggest that glucagon would adopt an unusual or dynamically fluctuating conformation in solution. Therefore, detailed conformation and molecular dynamics of glucagon would be worthy of investigation, for which the present results provide an experimental basis.