Isolation and characterization of four protein fractions of gluten by conventional methods

Many gluten components have been reported, but their physicochemical properties are rarely reported due to the small amount of preparation. In this research, ω-gliadin, αβγ-gliadin, alkali-soluble and urea-soluble glutenin (ASG and USG) fractions were isolated by conventional methods and characterized by molecular weights, disulfide bond contents, amino acid compositions, Ultraviolet (UV) absorption, FTIR and 13C Solid-state NMR Spectroscopy. The results showed that purified ω-gliadin, αβγ-gliadin, ASG and USG could be obtained by conventional methods on a large scale (approximately 9.67%, 12.43%, 6.00% and 18.26%, respectively). The UV absorption of gluten components in the helical and randomly coiled state could not be detected. The molecular weights of purified ω-gliadin, αβγ-gliadin, ASG and USG were all ~38500g/mol and their disulfide bond contents were 0.076, 0.374, 0.086 and 0.576 μmol/g, respectively. USG is characterized by free Glu and redundant Met, Phe and Ile. The distinctively diffraction angles of the gluten component monomers were 2θ at 22 o, 24 o, 29 o and 35 o. This study will be of great reference value for the industrial application of these newly isolated proteins in gluten production.