Browsing by Author "Rout, MK"

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    Effects of thermal denaturation on the solid-state structure and molecular mobility of glycinin
    (American Chemical Society, 2011-06-01) Huson, MG; Strounina, EV; Kealley, CS; Rout, MK; Church, JS; Appelqvist, IAM; Gidley, MJ; Gilbert, EP
    The effects of moisture and thermal denaturation on the solid-state structure and molecular mobility of soy glycinin powder were investigated using multiple techniques that probe over a range of length and time scales. In native glycinin, increased moisture resulted in a decrease in both the glass transition temperature and the denaturation temperature. The sensitivity of the glass transition temperature to moisture is shown to follow the Gordon-Taylor equation, while the sensitivity of the denaturation temperature to moisture is modeled using Flory's melting point depression theory. While denaturation resulted in a loss of long-range order, the principal conformational structures as detected by infrared are maintained. The temperature range over which the glass to rubber transition occurred was extended on the high temperature side, leading to an increase in the midpoint glass transition temperature and suggesting that the amorphous regions of the newly disordered protein are less mobile. C-13 NMR results supported this hypothesis. © 2011, American Chemical Society
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    Hydration induced structural changes in native, denatured and protected soy glycinin (11s)
    (Institute of Food Technologists, 2007-07) Appelqvist, IAM; Rout, MK; Chanvrier, H; Dezfouli, M; Kelly, M; Htoon, AK; Kealley, CS; Gilbert, EP; Strounina, E; Whittaker, AK; Gidley, MJ; Lillford, PJ
    Proteins and other biomolecules undergo a dynamic transition to a glass-like solid state with small atomic fluctuations. This dynamic transition can inhibit biological function and alter their material properties.
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    Structure and molecular mobility of soy glycinin in the solid state
    (American Chemical Society, 2008-10) Kealley, CS; Rout, MK; Dezfouli, MR; Strounina, E; Whittaker, AK; Appelqvist, IAM; Lillford, PJ; Gilbert, EP; Gidley, MJ
    We report a multitechnique study of structural organization and molecular mobility for soy glycinin at a low moisture content (<30% w/w) and relate these to its glass-to-rubber transition. Small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy are used to probe structure and mobility on different length and time scales. NMR (similar to 10(-6) to 10(-3) s) reveals transitions at a higher moisture content (> 17%) than DSC or SAXS, which sample for much longer times (similar to 10 to 10(3) s) and where changes are detected at > 13% water content at 20 degrees C. The mobility transitions are accompanied by small changes in unit-cell parameters and IR band intensities and are associated with the enhanced motion of the polypeptide backbone. This study shows how characteristic features of the ordered regions of the protein (probed by SAXS and FTIR) and mobile segments (probed by NMR and DSC) can be separately monitored and integrated within a mobility transformation framework. © 2008, American Chemical Society