Selenium accumulation in protein fractions during germination of Se-enriched brown rice and molecular weights distribution of Se-containing proteins

This study investigated the accumulation of selenium (Se) in protein fractions of albumin, globulin, prolamin and glutelin extracted from Se-enriched brown rice and the molecular weight distribution of Se-containing proteins. Results showed that the amount of total Se (T-Se) and protein-bound Se (PB-Se) in brown rice was significantly (P < 0.05) increased after germination with 10–60 μmol/l sodium selenite. Except prolamin, the amount of all the other three protein fractions decreased significantly (P < 0.05) with the increase of germination time. Low Se concentrations had promoting effects on degradation of albumin and globulin, while no significant effects were observed on prolamin and glutelin. The accumulation of T-Se and PB-Se were in the order of albumin > glutelin > globulin > prolamin. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS–PAGE) analysis showed that Se was distributed in all the proteins of which molecular weights varied from 13.6 to 121.4 kDa; however, 84.34% of Se was observed in the proteins whose molecular weights less than 36.3 kDa.

Research highlights
► The accumulation kinetics Se in brown rice during germination was investigated.
► Se accumulation capacity of various protein fractions of brown rice was studied.
► Determined molecular weights of Se-containing proteins in Se-enriched brown rice.
► A very non-uniform distribution of Se in Se-containing proteins was observed.