Marked activation of the N-acylphosphatidylethanolamine-hydrolyzing phosphodiesterase by divalent cations

Abstract

N-Acylethanolamines including anandamide (an endogenous ligand for cannabinoid receptors) are released from N-acylphosphatidylethanolamine ( N-acyl-PE) by the catalysis of a phosphodiesterase of the phospholipase D type. The enzyme was solubilized from the particulate fractions of rat heart with the aid of octyl glucoside, and partially purified by anion-exchange chromatography. The enzyme hydrolyzed N-palmitoyl-PE with a specific activity of 17 nmol/min/mg protein at 37°C. The enzyme activity increased dramatically up to 30-fold by millimolar order of Ca 2+. Ca 2+ could be replaced with other divalent cations such as Co 2+, Mg 2+, Mn 2+, Ba 2+, Sr 2+ and Ni 2+. The hydrolysis of N-arachidonoyl-PE (a precursor of anandamide) was also markedly stimulated by Ca 2+.