A 1H-n.m.r. study of casein micelles

Abstract

The 1H-NMR spectrum of casein micelles [from cow''s milk] consists of a small number of moderately sharp (linewidth .apprx. 60 Hz) resonances superimposed on the envelope of very broad lines expected for particles of this size. These sharp lines resemble, in chemical shift and relative intensity, the spectrum of the isolated macropeptide released from the micelles by treatment with chymosin. The sharp lines in the casein micelle spectrum are further sharpened by addition of chymosin and broadened markedly by addition of ethanol. The macropeptide (the C-terminal 64 residues of .kappa.-casein) forms flexible hairs on the surface of the micelles.