N. Ueda, K. Yamanaka, Shozo Yamamoto
Sep 21, 2001
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20
Influential Citations
234
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Journal
The Journal of Biological Chemistry
Abstract
N-Arachidonoylethanolamine (anandamide) is cannabimimetic, and N-palmitoylethanolamine is anti-inflammatory and immunosuppressive. We found an amidase that is more active with the latter than the former in contrast to the previously known anandamide amidohydrolase for whichN-palmitoylethanolamine is a poor substrate. Proteins solubilized by freezing and thawing from the 12,000 ×g pellet of various rat organs hydrolyzed [14C]N-palmitoylethanolamine to palmitic acid and ethanolamine. The specific enzyme activity was higher in the order of lung > spleen > small intestine > thymus > cecum, and high activity was found in peritoneal and alveolar macrophages. The enzyme with a molecular mass of 31 kDa was purified from rat lung to a specific activity of 1.8 μmol/min/mg protein. Relative reactivities of the enzyme with variousN-acylethanolamines (100 μm) were as follows:N-palmitoylethanolamine, 100%;N-myristoylethanolamine, 48%;N-stearoylethanolamine, 21%; N-oleoylethanolamine, 20%;N-linoleoylethanolamine, 13%; anandamide, 8%. The enzyme was the most active at pH 5 and was activated 7-fold by Triton X-100. The enzyme was almost insensitive to methyl arachidonyl fluorophosphonate, which inhibited anandamide amidohydrolase potently. Thus, the new enzyme referred to asN-palmitoylethanolamine hydrolase was clearly distinguishable from anandamide amidohydrolase.