Lipase Activity of Guinea Pig Peritoneal Macrophages and Mycobacterial Lipase Inhibitor

The interaction of mycobacterial lipase inhibitor (MLI), isolated from culture supernatant　fluid of Mycobacterium tuberculosis strain H37Rv, and lipase from guinea pig　peritoneal macrophages (GP-PMφs) was investigated fluorimetrically by the modified　lipase assay system which had previously been proposed.

Two peaks of lipase activity were observed in the enzyme preparation from GPPMφs. The activity of MLI against lipase from GP-PMφs was significantly high at acidic pH less than 5.0, and the pattern of inhibition was non-competitive.

Two types of lipase were isolated from the enzyme solution prepared from GPPMφs by an ion-exchange chromatography on a DEAE-Sepharose column. One of these acted only at pH 4.5 and was considered to be a lysosomal acid lipase, but another showed the activity at both pH 4.5 and 7.0. The former was four times more sensitive to the activity of MLI than the latter as well as the crude enzyme preparation.