Stokes radius of Casein

Range α-casein 2.9: β-casein 3.7 nm
Organism Cow Bos Taurus
Reference Marchesseau S, Mani JC, Martineau P, Roquet F, Cuq JL, Pugnière M. Casein interactions studied by the surface plasmon resonance technique. J Dairy Sci. 2002 Nov85(11):2711-21. link p.2714 right column 2nd & 3rd paragraphs PubMed ID12487438
Primary Source Andrews, A. L., D. Atkinson, M. T. A. Evans, E. G. Finer, J. P. Green, M. C. Phillips, and R. N. Robertson. 1979. The conformation and aggregation of bovine β-casein A. I Molecular aspects of thermal aggregation. Biopolymers 18: 1105–1121. DOI: 10.1002/bip.1979.360180507
Method surface plasmon resonance (SPR)
Comments P.2714 right column 2nd & 3rd paragraphs: "At pH 7.4 in the presence of CaCl2 (2 mM) and at acidic pH (pH 5.4), the proteins were also present as a monomer in solution (Stokes radius of 29 A° and 30 A°, respectively, Figure 1a). In most cases, there were also some high molecular weight multimers eluted in the void volume of the column (>100kDa). Dephosphorylated αs-caseins were eluted as a monomer (Stokes radius of 28 to 29 A°), and no dimer was detected at pH 7.4 or at pH 5.4 with the presence of calcium (Figure 1d). There were still, however, some high molecular weight multimers. At 4°C, β-casein is a monomer and behaves as a protein with a Stokes radius of 37A° (primary source)." Stokes-Einstein radius, or hydrodynamic radius RH, named after George Gabriel Stokes, is not the effective radius of a hydrated molecule in solution as often mentioned. Rather it is the radius of a hard sphere that diffuses at the same rate as the molecule. The behavior of this sphere includes hydration and shape effects. Values are for alpha (2.9 nm) and beta (3.7 nm )casein. See BNID 101827
Entered by Uri M
ID 103862