Fast protein liquid chromatography purification of hydrophobic fraction of bovine milk proteose-peptone and characterization by bidimensional electrophoresis

Bovine milk Hydrophobic fraction of proteose-peptone was prepared by hydrophobic interaction fast protein liquid chromatography. This method has several advantages such as high rapidity, simple good reproducibility and less denaturation. The proteose-peptone was eluted from a TSK-Phenyl-5PW column with a 1 M-0 M ionic strength gradient of NaH 2 PO 4 , pH 6·8, using a 6 ml/min flow rate for 56 min. The quantity of protein injected was 62·5 mg; however, it could be increased up to 100 mg. The elution order was β -CN-4P β -CN-5P β -CN-1P. The hydrophobic fraction was obtained in pure water at the end of the gradient (17·3% of total N). A proteose-peptone cartograph was achieved by bidimensional electrophoresis. This hydrophobic fraction represented three principal zones of M r 30000–28000, 19000 and 11000, which were respectively composed of 13, 4 and 2 principal spots distributed between 4·9 and 6·1 isoelectric points (IP). These spots corresponded to glycoproteins. ·7, 5·0 and 5·1 IP which migrated to M r 18000 while β -CN-1P was identified as M r 9000 in two spots of 5·1 and 5·3 IP.