Lactotransferrin (LF) is a large globular protein in milk with immunoregulatory and bactericidal properties. At pH =6.5 LF (M=78kDa) carries a net (calculated) charge of +21. Alpha S1, beta-casein and kappa-casein are part of the casein micelle complex in milk. The caseins (*CN) are amphiphillic proteins with a molar mass of 23kDa, 24kDa and 19kDa respectively. At neutral pH the CN’s carry net negative charges. Both BCN and KCN form soap-like micelles with 40 (BCN) and 65 (KCN) monomers. The net negative charges are located in the corona of the micelles. On mixing LF with the caseins coacervates are formed. We analysed the stability, composition and structure using SAXS. It is found that LF binds to the corona of the micellar structures, at the charge neutrality point. For BCN the ratio BCN/LF ≈1.2 and for KCN/LF≈5 at the charge neutrality point.
Prof. C.G. (Kees) De Kruif Kees.dekruif@NIZO.COM
