title: Role of γ-kafirin in the formation and organization of kafirin microstructures.
abstract: The possible importance of the cysteine-rich γ-prolamin in kafirin and zein functionality has been neglected. The role of γ-kafirin in organized microstructures was investigated in microparticles. Residual kafirin (total kafirin minus γ-kafirin) "microparticles" were non-discrete (amorphous mass of material), as viewed by electron microscopy and atomic force microscopy. Adding 15% γ-kafirin to residual kafirin resulted in the formation of a mixture of non-discrete material and nanosize discrete spherical structures. Adding 30% γ-kafirin to the residual kafirin resulted in discrete spherical nanosize particles. Fourier transform infrared spectroscopy indicated that γ-kafirin had a mixture of random-coil and β-sheet conformations, in contrast to total kafirin, which is mainly α-helical conformation. γ-Kafirin also had a very high glass transition temperature (Tg) (≈270 °C). The conformation and high Tg of γ-kafirin probably confer structural stability to kafirin microstructures. Because of its ability to form disulfide cross-links, γ-kafirin appears to be essential to form and stabilize organized microstructures.
authors.affiliation: Institute for Food, Nutrition and Well-being and Department of Food Science, University of Pretoria , Private Bag X20, Hatfield 0028, South Africa.
authors.forename: Joseph O
authors.initials: JO
authors.lastname: Anyango
authors.forename: John R N
authors.initials: JR
authors.lastname: Taylor
authors.forename: Janet
authors.initials: J
authors.lastname: Taylor
mesh_terms: D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D010940:Plant Proteins / Q000737:chemistry / Q000648:ultrastructure*; D055315:Prolamins / Q000737:chemistry; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D010940:Plant Proteins; D055315:Prolamins; C080615:kafirin protein, Sorghum bicolor