Circular dichroism and 13C nuclear magnetic resonance spectroscopy of pennisetin from pearl millet
Sainani, M.N.; Mishra, V.K.; Gupta, V.S.; Ranjekar, P.K.
Plant Science 83(1): 15-22
The conformation and stability of pearl millet prolamin (pennisetin) were examined by using circular dichroism and 13C nuclear magnetic resonance spectroscopy. The far UV spectrum of pennisetin in 70% (v/v) aqueous ethanol showed the presence of predominant a helical structure and its occurrence in the a + ß class of protein. The far and near UV spectra of pennisetin in ethanol: trifluoroethanol also supported this observation. However pennisetin showed the presence of some helical structure in 8 M urea which is known to be a highly unordered structure forming solvent. A decrease in a helical content of native pennisetin was observed with rise in temperature from 5-75°C and this effect of temperature was found to be reversible. A 13C NMR spectrum of pennisetin in 70% ethanol suggested a high degree of molecular mobility in ethanol. Comparison of the cross polarization spectrum with the single pulse excitation spectrum suggested pennisetin to be a heterogeneous protein.