a1 National Institute for Research in Dairying, Shinfield, Reading
The folate in cow's milk was strongly and specifically bound to a minor whey protein (FP), forming a complex of primary M of about 38000, but exhibiting concentration-dependent reversible aggregation. The binding protein was present in excess, and the milk had the capacity to bind about 50 μg added folic acid/l. An enriched concentrate of FP was prepared by ammonium sulphate fractionation—FP was precipitated at between 50 and 60% saturation—and further purified by chromatography in DEAE-cellulose and filtration in Sephadex gel G150. Its identity as a distinct minor whey protein was confirmed by comparative starch gel electrophoresis at various pH values.
Some properties of the protein are described, and its physiological significance discussed.
(Received June 12 1969)