Structural Analysis of Glucagon in Aqueous and Organic Solvents Using Microfluidic Modulation Spectroscopy

Abstract

Peptide drugs such as glucagon often face solubility and stability challenges that necessitate the use of organic solvents like dimethyl sulfoxide (DMSO), particularly in early discovery and screening stages. However, structural characterization of peptides in DMSO is difficult for most conventional biophysical techniques due to solvent interference. In this study, we applied Microfluidic Modulation Spectroscopy (MMS) to quantify the secondary structure of glucagon in increasing concentrations of DMSO and at varying pH conditions.

MMS revealed a progressive reduction in intermolecular β-sheet content and an increase in α-helical and turn structures with increasing DMSO concentration, indicating a shift toward monomeric, helical conformations. Lowering the pH further enhanced α-helix formation and suppressed aggregation-prone β-sheets. These results highlight the ability of MMS to deliver high-resolution, quantitative secondary structure data for peptides in organic solvent environments, providing critical insights for early-stage peptide drug development where organic solvents like DMSO are frequently required.