The Bile-Salt-Stimulated Lipase in Human Milk. Purification and Characterization

Abstract

The bile-salt-stimulated lipase was purified from human whey by chromatography on heparin-Sepharose and Affi-Gel blue. The purified enzyme gave a single band with a MW of 90,000 on dodecylsulfate/polyacrylamide gels; this band accounted for at least 98% of the protein on the gel. An antiserum to the purified lipase completely inhibited the enzyme activity and gave a single precipitate against human whey and purified lipase. The bile-salt-stimulated lipase was inhibited by DFP, which bound to the purified enzyme in a molar ratio of 0.85 mol/mol. The lipase is a glycoprotein with a high content of acidic amino acid residues and an isoelectric point of .apprx. 4. Proline constitutes > 10% of the total amino acid residues. The purified lipase has a turnover number of .apprx. 150 s-1.