Effect of reverse micelle on conformation of soy globulins: A Raman study

Raman spectroscopy was applied to investigate the main and side chain conformational changes of 7S and 11S globulins from soybean proteins using aqueous buffer and reverse micelle extraction. The 7S and 11S globulins using two extraction methods displayed typical spectral features (such as amide I, III region and the side chain conformations of particular residues) due to characteristic amino acid composition and molecular conformation. In comparison, the degree of molecular disorder increased in both globulins using reverse micelle extraction and new bands appeared. The relative amount of different structures of 7S and 11S globulins could be estimated through accurate measurement of the band intensities. Finally, the increase of the I850/830 intensity ratio of Raman tyrosine doublet in 11S globulin with reverse micelle extraction suggested a change towards a more exposed state of tyrosine residues, in good agreement with the more disordered conformation taken upon reverse micelle.