An insight into molecular motions and phase composition of gliadin/glutenin glycerol blends studied by C-13 solid-state and H-1 time-domain NMR

Monitoring of the molecular motions and secondary structures of gliadin (Gli) and glutenin (Glu) in blends with 10, 20, 30, and 40% glycerol was performed by solid-state (SS) and time domain (TD) NMR spectroscopy. Increasing the glycerol content increased the relative amount of -sheets and disordered structures, while decreasing -helices in Gli/Glu-glycerol blends studied by C-13 CPMAS NMR. For 20% glycerol samples, the protein side-chain mobility increased similarly for Gli and Glu. A higher proportion of -helices versus -sheets was found in Gli-glycerol blends compared with Glu-glycerol blends. Glycerol acted as immobilized in 10-20% glycerol Gli samples and was found mainly free in 30 and 40% glycerol Gli/Glu samples. During temperature experiments, 30 and 40% glycerol amounts impacted the dynamic molecular behavior of the Gli and Glu proteins differently than lipids, as observed by TD-NMR. The combination of TD-NMR together with SS-NMR showed details of the dynamic molecular variations in Gli/Glu protein structure and are promising techniques to monitor the molecular dynamics of plasticized proteins. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 739-750