LAUSR

Abstract The glass-forming concentration and the cooling effect of aqueous DMSO solutions at various concentrations X (mol%DMSO) on protein state were investigated using Raman spectroscopy and Fourier-transform infrared (FTIR) spectroscopy along with differential thermal analysis (DTA) to obtain fundamental information on storage of recombinant protein at cryogenic temperature. DTA and Raman spectral measurements showed that the aqueous DMSO solutions with lysozyme formed the glassy state at X = 15–60. Activity and structural stability of lysozyme in aqueous DMSO solutions before and after cooling exhibited small change up to X = 0–30. Thus, the DMSO concentration at X = 15–30 was found to be a suitable condition for lysozyme storage at cryogenic temperature. The cryopreservation ability of aqueous DMSO solutions for lysozyme was observed to be strongly associated with the glassy solution structure that inhibits protein unfolding and aggregation. The present findings may serve as basic information regarding the appropriate experimental conditions for DMSO solutions to be employed as a suitable cryoprotectant for various recombinant proteins.