Novel endogenous N-acyl glycines identification and characterization.

Discovery of the endogenous cannabinoid and N-acyl amide, anandamide (N-arachidonoyl ethanolamine), paved the way for lipidomics discoveries in the growing family of N-acyl amides. Lipidomics is a field that is broadening our view of the molecular world to include a wide variety of endogenous lipid signaling molecules. Many of these lipids will undoubtedly provide new insights into old questions while others will provide broad platforms for new questions. J Michael Walker's last 8 years were dedicated to this search and he lived long enough to see 54 novel lipids isolated from biological tissues in his laboratory. Here, we summarize the biosynthesis, metabolism and biological activity of two of the family of N-acyl glycines, N-arachidonoyl glycine and N-palmitoyl glycine, and introduce four additional members: N-stearoyl glycine, N-linoleoyl glycine, N-oleoyl glycine, and N-docosahexaenoyl glycine. Each of these compounds is found throughout the body at differing levels suggesting region-specific functionality and at least four of the N-acyl glycines are regulated by the enzyme fatty acid amide hydrolase. The family of N-acyl glycines presented here is merely a sampling of what is to come in the continuing discovery of novel endogenous lipids.