The heterogeneous substructure of casein micelles evidenced by SAXS and NMR in demineralized samples

The casein micelle (CM) have been described as a protein assembly held together by interactions between phosphoryl groups from the moieties, and several internal calcium phosphate nanoclusters (CCPs). While presence of inhomogeneities at small scale, sequestering CCPs, has widely accepted, medium scale inhomogeneities, so-called “Hard” regions, its relationship with object debate. In present work, solid state NMR SAXS data combined to study correlation removal CCPs structural modification micelle. A « native » sample three different demineralized ones; 5% (DM-05), 10% (DM-10), 25% (DM-25) in relation «native», analyzed. show that reduction total amount phosphorous ions (−5%, −10% −25% respectively) samples is not always equivalent loss measured decrease colloidal 31P (−15 −17% samples. also indicate, demineralization induces depletion some CCP while leaving remaining cluster rather like structure. good decreases intensity for spectral features associated nanoclusters. Finally, larger (the so called regions). However, this directly correlated (as NMR) indicating these regions may be, least partially, maintained large protein-protein interaction network. results are discussed compared models