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Separation and Quantification of HMW Glutenin Subunits by Capillary Electrophoresis¹

¹Published with the approval of the Director, Agricultural Experimental Station, North Dakota State University, Fargo, ND 58105. ²Department of Cereal and Food Sciences, North Dakota State University, Fargo, ND 58105-5728. ³Corresponding author. E-mail: Khalil.Khan@ndsu.nodak.edu

The use of capillary electrophoresis in SDS (SDS-CE) for separation and quantification of HMW glutenin subunits (HMW-GS) was investigated. HMW-GS were precipitated with 40% acetone from 50% 1-propanol extract of flour under reducing conditions after removal of monomeric proteins with 50% 1-propanol. Poly (ethylene oxide) was used in the running buffer (3% w/v) for SDS-CE. The results indicated that HMW-GS could be well separated by SDS-CE, including subunits 7+8, 7+9, 2+12, 5+10, and 17+18. However, HMW-GS showed delayed migration times compared with molecular weight protein standards. Some HMW-GS were reversed in their mobilities in SDS-CE compared with their mobility and molecular weights by SDS-PAGE. Therefore, the SDS-CE was unsuitable for MW determination of HMW-GS. A linear response was obtained from SDS-CE of a plot of the concentration of HMW-GS of the 40% acetone precipitate versus corrected areas for absorbance at 214 nm. Quantification of HMW-GS for the two biotypes (subunits 5+10 vs. 2+12) of an Australian wheat cultivar Warigal confirmed the differences between the two biotypes in their quantity of HMW-GS. Therefore, the technique could be used to quantify HMW-GS in conjunction with SDS-PAGE.