PROPERTIES OF LYSOPHOSPHOLIPASE IN MYCOBACTERIUM-LEPRAE

Lysophospholipids are key intermediates in the metabolism of phospholi pids. Cytoplasmic membranes of both eukaryotes and prokaryotes are mad e of phospholipid bilayers. Phospholipases are activated during phagoc ytosis. Lysophospholipids generated by phospholipase A(2) or A(1) degr ade cell membranes and can cause cell lysis. An active lysophospholipa se, that hydrolyzes lysophospholipids, was detected by the radioisotop e technique in Mycobacterium leprae. About two-thirds of the enzyme wa s particulate and one-third cytoplasmic. Optimum activity was at 37 de grees C, and at pH 6.0. Temperatures above 70 degrees C completely ina ctivated the enzyme. The compound AACOCF3, a trifluromethylketone anal og of ara chiodonic acid, inhibited the activity; the inhibition appea red to be of the uncompetetive type. The K-m of the enzyme was 2.5 x 1 0(-4) M, suggesting a fairly strong affinity for the substrate. Lysoph ospholipids have been shown to be microbicidal to invading organisms. Possession of lysophospholipase by M. leprae is apparently one of the methods by which the bacilli overcome the defense mechanisms of the ho st.