Identification of endogenous acyl amino acids based on a targeted lipidomics approach

Bo Tan,David K O’Dell,Y William Yu,M Francesca Monn,H Velocity Hughes,Sumner Burstein,J Michael Walker

doi:10.1194/jlr.m900198-jlr200

Abstract

Using a partially purified bovine brain extract, our lab identified three novel endogenous acyl amino acids in mammalian tissues. The presence of numerous amino acids in the body and their ability to form amides with several saturated and unsaturated fatty acids indicated the potential existence of a large number of heretofore unidentified acyl amino acids. Reports of several additional acyl amino acids that activate G-protein coupled receptors (e.g., N-arachidonoyl glycine, N-arachidonoyl serine) and transient receptor potential channels (e.g., N-arachidonoyl dopamine, N-acyl taurines) suggested that some or many novel acyl amino acids could serve as signaling molecules. Here, we used a targeted lipidomics approach including specific enrichment steps, nano-LC/MS/MS, high-throughput screening of the datasets with a potent search algorithm based on fragment ion analysis, and quantification using the multiple reaction monitoring mode in Analyst software to measure the biological levels of acyl amino acids in rat brain. We successfully identified 50 novel endogenous acyl amino acids present at 0.2 to 69 pmol g(-1) wet rat brain.

Highlights

Using a partially purified bovine brain extract, our lab identified three novel endogenous acyl amino acids in mammalian tissues
Earlier we reported the presence of N-arachidonoyl glycine (NAGly) and N-arachidonoyl gamma aminobutyric acid (GABA) in rats [11], which produced anti-inflammatory and anti-nociceptive effects [11,12,13,14]
We designed a computer program known as information dependent acquisition (IDA) Analyzer to analyze more than one thousand spectra generated in IDA experiments with the more than one hundred possible acyl amino acids

Summary

Introduction

Using a partially purified bovine brain extract, our lab identified three novel endogenous acyl amino acids in mammalian tissues. A family of lipids similar to acyl amino acids, containing only one amide bond connecting a fatty acid with dopamine, amine, or ethanolamine, has been identified in mammalian tissues. These have gained prominence with the identification of the endocannabinoid N-arachidonoyl ethanolamide [6]. More recent reports of acyl amino acids with biological effects in mammalian tissues include N-arachidonoyl serine, a vasodilator [16]; a series of N-acyl taurines [17] including N-arachidonoyl taurine, a TRPV1, and TRPV4 receptor activator [18]; and N-palmitoyl glycine, which inhibits the heatevoked response of nociceptive neurons in the rat dorsal horn [19].

Methods

Results

Conclusion