Properties of monoacylglycerol lipase in rabbit aorta

Monacylglycerol lipase activity was characterized in a soluble preparation from rabbit aorta (intima-media) obtained by combining a 100,000 x g supernatant fraction with activity solubilized from the 100,000 x g precipitate fraction by treatment with Triton X-100. Rates of hydrolysis with 1-monoolein and 2-monoolein substrates were nearly identical. 1-Monoolein was a competitive inhibitor (Ki 65 microM) of 2-monoolein hydrolysis. 2-Monoolein and 2-monopalmitin were both hydrolyzed more rapidly than 2-monoarachidonin. Lipase activity measured with a 2-monoolein substrate was inhibited by the addition of oleate, NaF and CaCl2 to the assay. Preincubation of the lipase preparation with p-bromophenacyl bromide resulted in a potent inhibition of lipase activity; this inhibition could be prevented by dithiothreitol.