Location: Grain Quality and Structure ResearchTitle: An improved method for extraction of sorghum polymeric protein complexes
Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2019
Publication Date: 11/8/2020
Publication URL: https://handle.nal.usda.gov/10113/6757033
Citation: Ioerger, B.P., Bean, S.R., Tilley, M., Lin, H. 2020. An improved method for extraction of sorghum polymeric protein complexes. Journal of Cereal Science. https://doi.org/10.1016/j.jcs.2019.102876.
Interpretive Summary: Sorghum proteins exist in grain in cross-linked large complexes. These cross-linked protein complexes are an important factor that impacts utilization of sorghum in food and ethanol industries and impacts the nutritional quality of sorghum. Despite the importance of these proteins complexes, methods to effectively extract and analyze intact cross-linked sorghum protein complexes are lacking. This research optimized an extraction method designed to extract sorghum proteins from flour while leaving protein complexes intact. This research will aid future projects focused on understanding how genetic variability, environmental stresses and processing all impact sorghum grain and flour quality.
Technical Abstract: A method for fractionating sorghum proteins using extraction solvents and techniques designed to obtain intact polymeric protein structures (especially disulfide linked) was developed. Extraction and separation conditions were optimized in terms of completeness of protein extraction, sample stability, and analytical resolution. After pre-extraction of albumins and globulins, a 3-step sequential procedure involving no reducing agents was applied to ground whole sorghum flour. The three fractions obtained represented proportionally different protein polymer contents and molecular weight distribution as evidenced by comparative size exclusion chromatography. Protein composition also varied among the extracts with differences in kafirin composition and non-kafirin proteins detected in the fractions by RP-HPLC and SDS-PAGE analysis. The ability to quantify and further characterize intact sorghum polymeric protein complexes will be useful for additional studies linking protein structures with functionality and digestibility and variations for these properties within diverse sorghum germplasm.