Physical Chemical Characterization of Grain Sorghum Prolamine Fractions and Components

T he proximate composition and proteins of three American grain sorghum hybrids were previously described (Jones and Beckwith, 1970). We noted that the prolamine class of protein from these hybrids readily formed gels in alcohol-water systems, as well as in such solvents as dimethyl sulfoxide and 8 M urea solutions. In the alcohol-water system the addition of 1.5 M guanidine hydrochloride (GHCI) prevented gel formation, whereas the addition of sulfhydryl blocking agents or disulfide bondbreaking compounds did not influence the gelling phenomena. As a continuing study of the properties of these proteins, we wish to report observed differences in solubility properties and amino acid composition between two fractions from the prolamines of the three hybrids used earlier. In addition, the sedimentation equilibrium behavior of these isolates was examined as a function of protein concentration and pH in solutions of 6 M GHCl which is considered to be strong noncovalent bond-disrupting agent.