Characterization of Kafirins in Algerian Sorghum Cultivars

Abstract

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.

Assessment of Algerian sorghum protein quality [Sorghum bicolor (L.) Moench] using amino acid analysis and in vitro pepsin digestibility

“…The following results confirm the hydrophobic characteristics of sorghum proteins. As shown in previous work, the major storage proteins of sorghum seeds are the alcoholic media extractable groups collectively known as kafirin which account for 60% or more of the total protein (Mokrane et al, 2006;Mokrane et al, 2009). The second most abundant amino acids were the acidic ones with levels around 23%, directly followed by the basic and the uncharged polar amino acids 16%.…”

“…In previous works, the protein fraction in Algerian sorghum cultivars was deeply characterized by size exclusion, reverse phase HPLC and SDS-PAGE (Mokrane et al, 2009) and the in vitro protein digestibility of the extracted proteins and the whole meal were determined and compared (Mokrane, Amoura, Belhaneche-Bensemra, & Nadjemi, 2006). The aim of this study was to investigate the nutritional quality of sorghum proteins in Algerian cultivars (amino acid composition and in vitro digestibility).…”

Genetic Basis of Protein Digestibility in Grain Sorghum

“…The most abundant kafirin subclass is the a-kafirins, which make up ?80 to 84% of the total kafirin fraction in vitreous endosperm and 66 to 71% in opaque endosperm (Watterson et al, 1993). There is a fourth subclass of kafirin, d-kafirin (M r = 15 kDa), which was recently characterized at molecular (Izquierdo et al, 2005) and protein levels (Mokrane et al, 2009;Cremer et al, 2014a). There is a fourth subclass of kafirin, d-kafirin (M r = 15 kDa), which was recently characterized at molecular (Izquierdo et al, 2005) and protein levels (Mokrane et al, 2009;Cremer et al, 2014a).…”

“…The g-kafirins accounts for 9 to 12% of the total kafirin fraction in vitreous endosperm and 19 to 21% in opaque endosperm, whereas b-kafirin comprises ?7 to 8% of total kafirins in vitreous endosperm and 10 to 13% in opaque endosperm (Watterson et al, 1993). There is a fourth subclass of kafirin, d-kafirin (M r = 15 kDa), which was recently characterized at molecular (Izquierdo et al, 2005) and protein levels (Mokrane et al, 2009;Cremer et al, 2014a). During maturation and drying of sorghum grain, kafirins undergo substantial polymerization with 30, 40, in this experiment was that the digestibility of the isolated protein body fraction was low, ranging only from 44.2 to 72.8%, depending on cultivar and cooked or uncooked state, suggesting that the protein body itself is highly resistant to digestion even after grain constituents perceived to interfere with digestion such as polyphenols, polysaccharides, and lipids were removed.…”

“…d-Kafirin is a very minor component of sorghum kafirins, accounting for <1% of total seed storage protein in mature grain (Laidlaw et al, 2010). For quite some time, it was only known at DNA sequence level until it was detected as a 15-kDa band in a protein gel loaded with high kafirin concentration (Mokrane et al, 2009) and was later confirmed via proteome sequencing (Cremer et al, 2014a). A lowly expressed single-copy gene in the centromeric region of sorghum chromosome 10 codes for d-kafirin (Izquierdo et al, 2005;Laidlaw et al, 2010).…”