Proteomics characterization of intermediate wheatgrass (Thinopyrum intermedium) flour proteins

Authors: GAJADEERA, CHATHURADA - University Of Minnesota; Ohm, Jae-Bom; LUU, MISEN - University Of Minnesota; MARKOWSKI, TODD - University Of Minnesota; HIGGINS, LEEANN - University Of Minnesota; ISMAIL, BARAEM - University Of Minnesota

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/18/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Thinopyrum intermedium, commonly known as intermediate wheatgrass (IWG), is a perennial crop with favorable agronomic characteristics and nutritional benefits. IWG lines are deficient in high molecular weight glutenins (HMWG), responsible for dough strength. A detailed characterization of IWG flour proteins has not been done before. Therefore, the aim of this study was to characterize flour proteins using a proteomics approach to better understand the bread-making quality parameters. Sixteen IWG lines along with one-bulk IWG sample and two wheat controls were analyzed for molecular weight distribution of flour proteins using size exclusion HPLC and were subsequently evaluated for bread-making quality. Total IWG flour proteins were extracted as SDS-soluble and SDS-insoluble proteins for bulk-IWG sample. The protein fractions were analyzed and identified by gel electrophoresis and LC-MS/MS respectively. MALDI-TOF was performed to determine the molecular weight of intact SDS-soluble and SDS-insoluble protein fractions. Total gluten proteins from bulk IWG were identified by LC-MS/MS. In contrast to wheat controls, IWG samples had lower percentage of SDS-unextractable high molecular weight polymeric proteins (uHMWPP). Relative quantity of soluble albumins and globulins were higher in IWG samples than that of wheat. HMWG, low molecular weight glutenin (LMWG), alpha, beta, gamma and omega–gliadins, and albumins and globulins were identified by LC/MS-MS as major proteins in IWG flour. These proteins were considerably different in their molecular weights as determined by MALDI-TOF in contrast to those of wheat controls. Similarly, the protein distribution and molecular weights of HMWG subunits in the IWG bulk sample were considerably different from wheat. HMWG present in IWG were of lower molecular weight, approximately 60 kDa compared to 80-120 kDa in wheat. These findings suggest that lower uHMWPP content in IWG samples results in poor dough rheology due to lack of gluten network formation. The detailed characterization of IWG flour proteins assists in figuring out solutions, such as use of dough conditioners, to enable utilization of the grain in baked products, and hence expand its market potential.