Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 4, 2005
Publication Date: April 4, 2005
Citation: Parris, N., Fett, W.F., Dickey, L.C., Moreau, R.A. Bioactive peptides from corn germ proteins. Meeting Abstract. 96th AOCS Annual Meeting & Expo. Salt Lake City, UT, May 1-5, 2005. Session PCP 1.1 Protein and Coproducts: Bioactive Peptides, Oral Paper 9. Technical Abstract: Traditionally, the value of dietary proteins has been assessed by evaluating nutritional quality - specifically the availability of essential and non-essential amino acids and the absence of co-existing anti-nutrients that can limit protein digestibility. In contrast, recently food proteins have been valued by assessing the potential availability of peptides that are biologically active. Several types of corn peptides have been reported to have biological activity. A group of corn tripeptides was reported to inhibit the angiotensin converting enzyme (ACE) and perhaps have applications for lowering blood pressure. Certain corn pentapeptides have been reported to have herbicidal activity. There have been reports of larger basic peptides (~4 KDa), isolated by acid extraction from corn kernels that exhibit antimicrobial properties. The development of new antimicrobial peptides is of practical importance as a result of increasing levels of bacterial resistance to antibiotics due to overuse in humans and livestock. As part of a project on the aqueous enzymatic extraction of oil from corn germ, the objective of our research was to develop bioprocesses to enhance the value of proteins from the de-oiled germ. Albumin and globulin proteins, in de-oiled commercial wet- and dry-milled corn germ, were extracted with saline solution followed by aqueous alcohol extraction of zein proteins from the residue after centrifugation. Approximately 70% more albumin and globulin protein and 35% more zein were isolated from dry-milled corn germ compared to wet-milled germ. The lower amounts of albumin and globulin in wet-milled germ can be attributed to losses during steeping. SDS-PAGE gel electrophoresis indicated that proportionally more alpha-zein was present in the dry-milled corn. This is probably an indication of endosperm components in the germ. Inhibitory activity of these proteins and their peptides, after hydrolysis with trypsin or thermolysin was determined against Escherichia coli O157:H7, Listeria monocytogenes or Salmonella Anatum. Unhydrolyzed zein and zein hydrolyzed with trypsin or thermolysin exhibited inhibitory activity against S. Anatum in initial bioassays. Additional antimicrobial bioassays are ongoing. Future studies will include treatment of germ proteins with other types of commercially available proteases or fermentation with Lactobacillus species that have been shown to generate bioactive peptides with proteins from other sources.