Some Peptides and Amino Acids Are Known to Have Metal Chelation Properties

Feb. 22, 2002

Department of Food SciencePresenter: Seong Jae Yoo

Initial Ph.D SeminarAdvisor: Dr. Thomas Hartman

Iron Chelation Peptides: An Alternative Approach to Inhibit Iron-Catalyzed Lipid Oxidation

Nutrient-fortified foods such as infant formulas are commonly formulated with higher concentrations of oils, proteins, vitamins and minerals than other food products. These components are necessary in infant formulas in order to improve nutritional quality so that Recommended Daily Allowance (RDA) can be met. The high concentrations of oils and metals often lead to lipid oxidation during processing and storage. Preventative strategies to reduce this problem such as the use of good quality oil, storage at low temperature and packaging under vacuum or inert gas have been applied in the infant formula industry. However, lipid oxidation catalyzed by transition metals (mainly iron) remains a major concern.

Casein phosphopeptides (CPP) from casein hydrolylsates have been used in the infant formula industry to improve the bio-availability of calcium in some Asian countries. CPP is also known to have a strong iron-chelation activity due to a sequence of phosphoseryl residues. If the iron-chelation activity of CPP can be shown to reduce iron-catalyzed lipid oxidation, this will identify another benefit of using CPP in nutrient-fortified foods. We hypothesize that the formation of Fe-CPP chelation complexes would reduce iron mobility in the food systemandthe catalytic activity of iron would be reduced. Consequently, the addition of CPP into foods containing high concentrations ofoil and iron would possibly inhibit the catalytic activity of iron in lipid oxidation.

During a preliminary study, the antioxidative activity of CPP against iron-catalyzed lipid oxidation was determined by the ferrous-thiocyanate method. CPP was shown to inhibit the generation of hydroperoxides. From this study, we deduce that iron chelation of CPP is able to reduce the oxidative catalytic activity of iron. Addition of CPP is an alternative approach to inhibit iron-catalyzed lipid oxidation. Future studies will include investigations into the antioxidative properties of CPP as a function of the amino acid sequence (e. g. molecular weight and hydrophobicity of residues).

References:

K.M. Schaich, “Metals and Lipid Oxidation. Contemporary Issues” Lipids, Vol. 37 (3) 209-218, 1992

R. J. FitzGerald, “Potential uses of Caseinophosphopeptides,” Int. Dairy Journal, 8: 451-457, 1998

M. T. Satue-Gracia, E. N. Frankel, N. Rangavajhyala, and J. B. German, “Lactoferrin in Infant Formulas: Effect on Oxidation,” J. Agri. Food Chem. 48: 4984-4990, 2000