Selenium modification of β-lactoglobulin (β-Lg) and its biological activity

beta-Lg is a major whey protein in cow's milk. This study was aimed to find a new kind of organic selenium compound synthesized with beta-Lg and selenium dioxide as raw materials under the conditions of vacuum and low temperature. Fourier transformed infrared spectroscopy revealed that seleno-beta-lactoglobulin (Se-beta-Lg) displayed a strong band at 878 cm(-1), belonging to Se=O. Circular dichroism spectra results indicated that the conformation of Se-beta-Lg was transformed and a-helical, and unordered structures were increased by 9% and 11.2%, respectively, while beta-sheet and beta-turn were reduced by 14.2% and 6%, respectively. Electrophoresis and matrix-assisted laser desorption/ionization time of flight mass spectrometry results showed that there were two protein bands (1-Se beta-Lg and 2-Se beta-Lg) in Se-beta-Lg, only one beta-Lg connected with selenate in 1-Se beta-Lg, but two beta-Lgs, connected to each other, and with selenate, in 2-Se beta-Lg. Morphological observation and hematoxylin and eosin staining indicated that Se-beta-lg could induce K562 cell apoptosis. These results indicated that Se-beta-Lg could be synthesized by selenium conjugating beta-Lg and it had antitumor activity. (C) 2016 Published by Elsevier Ltd.