Review and update of casein chemistry.
Of all food proteins, bovine milk proteins are probably the most well characterized chemically, physically, and genetically. The primary structures are known for most genetic variants of alpha s1-, alpha s2-, beta-, and kappa-caseins, beta-lactoglobulin, and alpha-lactalbumin. Secondary and tertiary structures of the whey proteins have been determined, and secondary structures of the caseins have been predicted from spectral studies. The caseins, although less ordered in structure and more flexible than the typical globular whey proteins, have significant amounts of secondary and, probably, tertiary structure. The amphipathic structure of the caseins is especially noteworthy; thus, these proteins most likely are divided into polar and hydrophobic domains. The presence of anionic phosphoseryl residue clusters in the calcium-sensitive casein polar domains is particularly significant because of their interaction with calcium ions, or calcium salts, or both, and the formation of micelles. Flexibility of casein structures is reflected by their susceptibilities to limited proteolysis, which dramatically changes functionality.
Swaisgood
H E
HE
Department of Food Science, North Carolina State University, Raleigh 27695-7624.
D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002364:Caseins / Q000032:analysis / Q000737:chemistry; D002417:Cattle; D008894:Milk Proteins / Q000737:chemistry / Q000235:genetics*; D015394:Molecular Structure; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D009626:Terminology as Topic
D002364:Caseins; D008894:Milk Proteins; D002118:Calcium