11-2 |
Characterization of hard red spring wheat cv. butte 86 prolamin proteins by revere phase HPLC, capillary electrophoresis in relation to viscoelastic behavior |
S. PATEL1, P. Rayas-Duarte2, and G. El-Rassi1. (1) Oklahoma Food & Agricultural Products Research & Technology Ctr., Oklahoma State Univ., 322 FAPC, Stillwater, OK 74078-6055, (2) Dept. of Biochemistry & Molecular Biology, Oklahoma State Univ., 148 Noble Research Ctr., Stillwater, OK 74078-3035 The viscoelastic properties of dough are strongly affected by wheat storage-proteins, gliadins and glutenins. Gliadins contribute to flow and glutenins to elasticity, but the molecular basis of the functionality of the protein network of gluten remains unclear. The objective of this study is to characterize gluten protein fractions based on their molecular weight distribution, hydrophobicity and surface charge, and relate them to viscoelastic behavior (by dynamic rheology) in both reduced and oxidized states. A procedure for the simultaneous extraction of high molecular weight (HMW) glutenins, low molecular weight (LMW) glutenins and gliadins based on their selective precipitation in 60%(v/v) propan-1-ol, 85%(v/v) propan-1-ol and 50%(v/v) propan-1-ol, respectively was used. Reverse phase high performance liquid chromatography (RP-HPLC) of the fractions was performed using a Vydac C-18 column using a linear gradient of 24% to 50% (v/v) acetonitrile. Subfractions of the most prominent peaks obtained by RP-HPLC were analyzed by capillary zone electrophoresis (CZE) using a fused silica column. Rheological studies were carried out with three ratios of HMW glutenin and gliadin fractions in a redox gel system with different concentrations of H2O2. HMW glutenin fraction had proteins ranging from 50–100kDa and LMW glutenin fraction from 10-40kDa as determined by SDS-PAGE. RP-chromatograms revealed that the HMW glutenins are more hydrophobic than the LMW glutenins. RP-chromatograms of the gliadin fraction (20-85kDa) showed at least 15 sharp peaks with a wide range of hydrophobic surface. Electropherogram fingerprints (CZE) show that the individual peaks collected from RP-HPLC are a mixture of proteins varying in their net surface charge. Electropherograms of the prolamin proteins were completed by including fingerprints of the major peaks of the LMW-glutenin and gliadin fractions. The viscoelastic behavior of each fraction and a mixture of the fractions in a reduced and oxidized state were compared to their biochemical properties.
Session 11, Food Chemistry: Proteins I
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