title: Structure and molecular mobility of soy glycinin in the solid state.
abstract: 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 (approximately 10(-6) to 10(-3) s) reveals transitions at a higher moisture content (>17%) than DSC or SAXS, which sample for much longer times (approximately 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.
authors.affiliation: Bragg Institute, Australian Nuclear Science and Technology Organization, PMB 1, Menai, NSW 2234 Australia.
authors.forename: Catherine S
authors.initials: CS
authors.lastname: Kealley
authors.forename: Manoj K
authors.initials: MK
authors.lastname: Rout
authors.forename: Mahshid Roohani
authors.initials: MR
authors.lastname: Dezfouli
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Strounina
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Whittaker
authors.forename: Ingrid A M
authors.initials: IA
authors.lastname: Appelqvist
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Lillford
authors.forename: Elliot P
authors.initials: EP
authors.lastname: Gilbert
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Gidley
mesh_terms: D002152:Calorimetry, Differential Scanning / Q000379:methods; D005916:Globulins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry; D012542:Scattering, Radiation; D030262:Soybean Proteins / Q000737:chemistry*; D013025:Glycine max / Q000378:metabolism*; D013055:Spectrophotometry, Infrared / Q000379:methods; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014867:Water / Q000737:chemistry; D014965:X-Rays
chemical_list: D005916:Globulins; D011506:Proteins; D030262:Soybean Proteins; D014867:Water; C011474:glycinin