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Arch Latinoam Nutr. 1992 Mar;42(1):46-51.

[Extraction and characterization of grain prolamins of 6 sorghum Sorghum bicolor L. Moench cultivars].

[Article in Spanish]

Author information

1
Instituto de Química y Tecnología, Facultad de Agronomía (UCV), Maracay, Venezuela.

Abstract

The purpose of this work was to isolate and characterize prolamines from grains of sorghum, by their solubility and molecular properties. One variety, Zaraza-1 (SV-V51), and five hybrids (Dekalb-55, Dekalb-64, Wac-5005, Pioneer-815B and Savanna-5) were used. The prolamines, called kafirins, were extracted with 70% isopropanol at 60 degrees C, and then fractionated by two methods: 95% ethanol and gel filtration with Sephadex G-200. The molecular weight was determined by electrophoresis in a discontinuous polyacrylamide gel with sodium dodecyl sulfate (PAGE-SDS). The alpha kafirin (soluble fraction in 95% ethanol), and 7.13% of the grain's total protein, and the beta kafirin represents 21.64% of kafirin (the insoluble fraction), represents 78.36% of the kafirin and 25.39% of total protein. Three fractions were obtained from the column fractionation, two important ones (A and C), and one (B) in a lesser amount. The proportion of these fractions varied between cultivars, so that in SV-V51, D-64 and Wac-5005, A is predominant, and in high tannin sorghum, C is the predominant one. Kafirins reduced with 2-mercaptoethanol were separated in four subunits with molecular weights of: 15,000, 21,300, 24,300 and 51,500 daltons. Unreduced kafirin showed a larger number of subunits (six) whose molecular weights were: 15,000, 24,300, 48,500, 69,000, 80,000 and 93,500 daltons. Reduced and kafirin showed the same number of subunits as those of nonfractioned kafirin reduced with 2-mercaptoethanol.

PMID:
1308645
[Indexed for MEDLINE]

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