Apparent Location of Lipase in Casein

The principal lipase in milk is known to be associated with the casein complex.In this study, the casein obtained from It,S-treated skimmilk separated by centrifugation at 50,000 r.p.m, possessed almost twice the lipase activity of the casein separated by acidification with 10% lactic acid.Sols of the casein separated by acidification and centrifugation were prepared in a borate buffer of pI-I 9.0.These sols were subjected to continuous paper electrophoresis which separated the casein complex into three fractions; presumably, the a-, ~-~ and -/-caseins.The collected effluents of the separated fractions were studied to determine if they were capable of causing breakdown of milk fat by incubating them in a milk fat substrate for 72 hr.Based on the increases in free fat acidities of these substrates, lipolytie activity was demonstrated only by those effluents bearing protein from the most rapidly migrating casein fraction (a-casein).