31P-nuclear magnetic resonance study of milk fractions

Abstract

SummaryMilk serum, whey and milk ultrafiltrate were examined by31P nuclear magnetic resonance (31P-NMR). About 20 phosphorylated milk constituents gave rise to resonances in the spectra. Most of these have been assigned to such well-known milk constituents as inorganic phosphate,N-acetylglucosamine-1-phosphate and glycerophosphorylcholine. Resonances from previously unknown constituents such as phosphocreatine were also observed. When the pH-dependence of inorganic phosphate,N-acetylglucosamine-1 -phosphate, glycerophosphorylcholine and gly-cerophosphorylethanolamine was examined it was observed that the resonance of inorganic phosphate overlapped that ofN-acetylglucosamine-1-phosphate around neutral pH. This is the most probable explanation as to why this constituent was not observed in earlier31P-NMR studies on milk.