Role of γ-kafirin in the formation and organization of kafirin microstructures

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Authors

Anyango, Joseph Ochieng
Taylor, J.R.N. (John Reginald Nuttall)
Taylor, Janet

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Publisher

American Chemical Society

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.

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Keywords

Kafirin microparticles, Disulfide cross-linking, Glass transition temperature, Secondary structure, Y-kafirin

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Citation

Anyango, JO, Taylor, JRN & Taylor, J 2013, 'Role of γ-kafirin in the formation and organization of kafirin microstructures', Journal of Agricultural and Food Chemistry, vol. 61, no. 45, pp. 10757-10765.