Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/2008
Publication Date: 9/21/2008
Citation: Jonnala, R., Bean, S., Lafiandra, D., Macritchie, F. 2008. Modified omega gliadins as chain terminators in Pegaso near-isogenic lines. Meeting Abstract. Cereal Foods World. 53:A30.
Technical Abstract: Unextractable polymeric protein (UPP) is a parameter that gives a relative measure of the molecular weight distribution (MWD) of the polymeric protein, based on solubility. For any glutenin subunit to participate in a growing polymer, it has to have at least two cysteine residues. Modified (mutated) gliadins of LMW-GS havin an odd number of cysteines or LMW compounds having one thiol group can act as chain terminators. This should shift the MWD towards lower values that in turn would be reflected in lower UPP values. Thus a higher number of omega-gliadins cross-linked to glutenins should correlate with UPP. Twenty four near-isogenic lines with the background of Pegaso bread wheat that have combination of variation at Glu-1, Gli-1/Glu-3 and Gli-2 loci were used for investigation. The goal of the study was to seek evidence for the 'role of chain terminators in decreasing UPP values' and to examine the influence of chain terminators on the MWD of gluten proteins. A novel method was developed to extract the omega-gliadins. Capillary electrophoresis (CE) and SEC-MALLS were used to quantify the omega-gliadins and to estimate the MWD, respectively. The moderately high negative correlation (R squared = 0.65) between reduced (SDS-RA) polymeric protein and modified omega-gliadins in CE suggests that these omega-gliadins act as chain terminators, resulting in smaller polymers, thus causing a reduction of UPP values. Results from SEC-MALLS indicated the significant differences amoung Pegaso NILs for MWD of the SDS-insoluble fraction.