Rehydration and structure of reconstituted casein micelles
Principal Investigators: Don McMahon, Utah State University
Synthesis of casein supramolecules in the mammary gland rely on a controlled synergy between two concomitant aggregation processes. Calcium phosphate is formed into clusters because of its low solubility, and caseins are simultaneously undergoing polymerization because of their calcium sensitivity and hydrophobic nature. Precipitation of calcium phosphate is limited to formation of nanoclusters by binding of caseins via their phosphoserine side chains, and the polymerization of the caseins is limited to colloidal size by the chain-terminating influence of k-casein. The irregular supramolecular structure for the colloidal casein particles in milk, supports an open structure in which different caseins can attach to calcium phosphate nanoclusters preventing calcium phosphate crystallization in the mammary gland. Chains of proteins can then grow until they encounter a chain-terminating protein or bond with another chain. Also, different dissociation and aggregation behavior of casein supramolecules may be explained using this model. Overall, this study has put forth a molecular model for the casein supramolecule that satisfies the principles of self aggregation, interdependence, and diversity that are often observed in nature.
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Oommen, B. S., and D. J. McMahon. 2002. Effect of method and time of hydration on structure of dried milk proteins. American Dairy Science Association Meeting, J. Dairy Sci. 85(Supp. 1):157.
Oommen, B. S., and D. J. McMahon. 2002. Coagulation properties of skim milk fortified with various dried milk proteins. American Dairy Science Association Meeting, J. Dairy Sci. 85(Supp. 1):380