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Characterization of Kafirins in Algerian Sorghum Cultivars

¹Laboratoire des produits bioactifs et de la valorisation de la biomasse, Ecole Normale Supérieure, BP 92, Kouba, Alger, Algérie. ²Département Génie de l'environnement, Ecole Nationale Polytechnique, BP 182, El Harrach, Alger, Algérie. ³Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), K.U. Leuven, Kasteelpark Arenberg 20, bus 2463, B-3001 Leuven, Belgium. ⁴Laboratory of Molecular Immunology, K.U. Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium. ⁵Corresponding author. Phone: +32(0)16321634. Fax: +32(0)16321997. E-mail: jan.delcour@biw.kuleuven.be

The prolamins in seven Algerian Sahara sorghum cultivars of varying seed shape and color were investigated. Protein contents ranged from 12 to 16%. Prolamins were the major protein fraction. They could be separated according to degree of disulfide cross-linking. Kafirin monomers and low molecular weight polymers could be extracted with 70% ethanol, whereas highly cross-linked kafirins additionally needed a reducing agent to become extractable. Kafirin monomers of α-, β- and γ-type were purified and N-terminally sequenced. For the first time, δ-kafirin was identified at the protein level. The study clearly revealed intercultivar differences between protein levels. The joint use of SDS-PAGE, SE-HPLC, and RP-HPLC allowed discriminating among cultivars based on the differences in prolamin levels and composition.