Fractionation and characterization of teff proteins

Abstract

The protein fractions in three different teff types were studied in comparison to sorghum to explain teff’s superior bread making quality. The proportion of aqueous alcohol-soluble teff proteinwas approx 40% and it was rich in glutamine and leucine. Hence, contrary to previous reports, prolamin is the major teff grain storage protein. With SDS-PAGE under non-reducing and reducing conditions, teff prolamins showed broad bands at approx. 20.3 and 22.8 kDa. Other bands were at approx. 36.1, 50.2, 66.2 and 90.0 kDa, respectively under non-reducing conditions, but were absent under reducing conditions, indicating that these polypeptides are disulphide bonded. The presence of broad monomeric prolamin bands in teff under non-reducing conditions indicates that teff prolamin is less polymerized than sorghum prolamin. Estimated free energy of hydration of teff prolamins was 161.3 kcal/mol compared to 139.8 kcal/mol for sorghum prolamin. By 2-D electrophoresis, teff protein contained more polypeptides than maize or sorghum. Teff contained a higher proportion of basic polypeptides than maize. With differential scanning calorimetry, teff prolamin exhibited a single endothermic peak at 69.85 C, while no peakwas detected for sorghum prolamin. The lower polymerization, hydrophobicity and denaturation temperature of teff prolamins probably make them somewhat functional in bread making