A new allele of gamma-kafirin gene coding for a protein with high lysine content in Mexican white sorghum germplasm

作者：Chiquito Almanza Elizabeth; Ochoa Zarzosa Alejandra; Lopez Meza Joel E; Pecina Quintero Victor; Nunez Colin Carlos A; Anaya Lopez Jose L^*

来源：Journal of the Science of Food and Agriculture, 2016, 96(10): 3342-3350.

DOI：10.1002/jsfa.7513

• white sorghum
• gamma-kafirin
• protein digestibility
• lysine content
• secondary structure
• disulfide bonds

BACKGROUND: Low protein digestibility and lysine content of white sorghum grain limit its use as a foodstuff. The increase in gamma-kafirin cross-linking, has an important role in the reduction of protein digestibility. The objective of this study was to characterize the gamma-kafirin gene in 12 Mexican tannin-free white sorghum genotypes and its relationship with protein digestibility and lysine content.
RESULTS: Two alleles of gamma-kafirin gene were identified: alleles 1 and 7. The predicted amino acid sequence of allele 7 showed seven point mutations; six were silent, and one missense (C235G), causing the substitution P79A in the deduced amino acid sequence. In silico analysis showed that gamma-kafirin codified by allele 1 has five alpha-helixes without disulfide bonds, while gamma-kafirin coding by allele 7 has four alpha-helixes and three disulfide bonds. Genotypes with allele 7 had higher lysine content than those with allele 1, showing no differences in the kafirin electrophoretic profile, neither a correlation with the protein content nor the in vitro pepsin digestibility.
CONCLUSIONS: Mexican tannin-free white sorghum genotypes showed two gamma-kafirin alleles, 1 and 7. Allele 7 was associated with higher lysine content; in silico analysis showed that the substitution of P79A in this allele could modify gamma-kafirin secondary structure.

• 出版日期2016-8-15