Phospholipid deacylating activities in murine leprosy bacilli

ABSTRACT

1) The particulate fraction of cultivated murine leprosy bacilli (Mycobacterium lepraemurium, rough colonies of the Hawaiian-Ogawa strain) contained phospholipid deacylating activities with acidic pH optima. It hydrolyzed phosphatidylcholine and phosphatidylethanolamine at similar rates, and phosphatidylinositol oligomannosides more slowly. It also hydrolyzed 1-acyl- and 2-acyl-GPCs (sn-glycerol 3-phosphocholine) more rapidly than phosphatidylcholine. 2) Ca2+ did not stimulate either diacyl- or monoacyl-hydrolase activity. Triton X-100 and Emulgen 913 had little influence on the hydrolysis of phosphatidylcholine, but at rather high concentrations inhibited the hydrolyses of 1-acyl- and 2-acyl-GPCs. Iron ions strongly inhibited the hydrolysis of phosphatidylcholine, but caused little or no inhibition of the deacylations of 1-acyl- and 2-acyl-GPCs. 3) With 1-[stearoyl-14C]phosphatidylcholine and 2-[oleoyl-14C]phosphatidylcholine as substrates, both labeled fatty acid and lysophosphatidylcholine were produced. Labeled fatty acid appeared more rapidly from 2-[oleoyl-14C]phosphatidylcholine than labeled lysophosphatidylcholine, while labeled lysophosphatidylcholine was produced more than labeled fatty acid from 1-[stearoyl-14C]phosphatidylcholine in the early stage of incubation.