Enzymes for anandamide biosynthesis and metabolism

Anandamide is an endogenous ligand for cannabinoid receptors. We tried to isolate and purify ‘anandamide amidohydrolase’ which hydrolyzes anandamide to arachidonic acid and ethanolamine. The enzyme activity was found in the microsomal fraction of procine brain homogenate. The enzyme was solubilized in 1% Triton X-100, and partially purified by hydrophobic chromatography to a specific activity of about 0.3 μmol/min per mg protein (37°C). Apparent K_m for anandamide was about 60 μM. The enzyme reacted also with also converted arachidonic acid to anandamide in the presence of 250 mM concentration of ethanolamine. Several lines of evidence including experiments using various inhibitors suggested that the anandamide synthase and amidohydrolase activities were derived from a single enzyme protein.