Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/14/2011
Publication Date: 1/8/2013
Citation: Farrell Jr, H.M., Brown, E.M., Malin, E.L. 2013. Higher order structures of the caseins: a paradox? In: McSweeney, P.L.H., Fox, P.F., editors. Advanced Dairy Chemistry, Volume 1A: Proteins: Basic Aspects, 4th edition. New York, NY: Springer Publisher. p 161-184.
Technical Abstract: This book chapter deals with the molecular architecture of the major milk proteins, the caseins. Earlier theories of casein structure classified them as random coils; i.e., flexible without definite structural elements. Recent advances in the field of protein chemistry have significantly enhanced our understanding of mechanisms of protein folding and have produced what is termed the “New View” of protein structure. In this chapter new structural analyses of the caseins are presented and interpreted with regard to the “New View” of protein folding. The caseins are now considered to be members of the class of proteins referred to as natively unfolded or molten globule. These proteins are characterized by an open structure, a high degree of hydration and a significant amount of native secondary structure with few tertiary folds. In fact, the caseins appear to react with each other using defined structural elements and proceed to quaternary structures without any tertiary folds. These features give the product, sodium caseinate, its reliable properties as a food ingredient and are responsible for calcium binding and transport from mammary gland to milk. The structural basis for the concept that the caseins are both structured and flexible may be explained, in part, by comparison with the architectural concepts of tensegrity. Application of these concepts to dairy products may lead to new uses for the caseins as functional food ingredients.