Cereal Chem 67:141-147   |  VIEW ARTICLE

Analysis by Reversed-Phase High-Performance Liquid Chromatography of Changes in High Molecular Weight Subunit Composition of Wheat Storage Proteins During Germination.

J. E. Kruger and B. A. Marchylo. Copyright 1990 by the American Association of Cereal Chemists, Inc. 

The breakdown of high molecular weight (WMW) glutenin subunits in Neepawa wheat was examined over a five-day germination period by reversed-phase high-performance liquid chromatography (RP-HPLC) and sodium dodecyl sulfate gradient polyacrylamide gel electrophoresis. Storage proteins were extracted sequentially (after preextraction with salt) with 50% 1-propanol, 50% 1-propanol containing 1% dithiothreitol (DTT), and 50% 1-propanol containing 4% DTT and 1% acetic acid. HMW glutenin was selectively precipitated from the 50% 1-propanol and 50% 1-propanol containing 1% DTT extracts, alkylated with 4-vinylpyridine, and individual subunits were analyzed quantitatively by RP-HPLC. The amount of HMW glutenin subunits extracted into 50% 1-propanol containing 1% DTT decreased throughout germination, whereas amounts of HMW subunits extracted into 50% 1-propanol remained nearly constant. The relative composition of HMW glutenin subunits, particularly in extracts of 50% 1- propanol containing 1% DTT, changed upon germination. Subunits 9 and 10 gradually disappeared, whereas subunits 5, 7, and 2* remained after five days of germination. On the other hand, in the 50% 1- propanol extractant, subunits 5 and 10 showed the greatest increases during germination. Only small amounts of HMW glutenin subunits were extracted with 50% 1-propanol containing 4% DTT and 1% acetic acid. The subunit composition of this extractant was different from that in the extractants preceding it and showed only small changes during germination. These results provide further insight into the relationship between storage proteins and the deterioration in wheat quality concomitant with preharvest sprouting.