Professor University of Manitoba Winnipeg, MB, Canada
Abstract: Food proteins have a similar linear structure with respect to the amino acid chain, which consists solely of peptide bonds. However, proteins differ depending on the type of group attached to the peptide bond backbone. Therefore, proteins contain unique amino acid sequences that are usually inactive within the primary structure. These sequences can be released as peptides through enzymatic hydrolysis in vitro or in vivo. Once released, the peptides have the ability to influence metabolic reactions and impart health benefits. In this presentation, the ability of proteins and peptides from hemp seed, soybean, and sunflower to influence various metabolic reactions is discussed. First, whole hemp seed and soybean proteins were fed to polycystic kidney disease rats with outcomes that showed reduced inflammation, kidney damage, and heart weight. Second, during a human intervention trial, the digested hemp seed proteins ameliorated hypertension and oxidative stress parameters, including reductions in blood pressure, plasma angiotensin converting enzyme, and total level of toxic peroxides. Third, the immunomodulatory effects of sunflower protein-derived peptides were demonstrated using cell culture experiments. The enzymatic digest of sunflower proteins was able to reduce IL-1β stimulated NFκB activation, but with enhanced IL-4/GM-CSF induced expression of surface markers CD14 and CD86. The increased expression of CD14 suggests an ability to enhance immune response to Gram-negative bacteria. YFVP, SGRDP, MVWGP and TGSYTEGWS were identified as novel peptides that reduced IL-1β stimulated NFκB activation. However, MVWGP was the most potent immunomodulatory peptide, which was attributed to the presence of methionine in the sequence. These studies illustrate the potential health-promoting properties of plant proteins and peptides, which could contribute to strengthening the activities of the functional foods and nutraceuticals industry.
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