Chemical proteomic analysis of palmostatin beta-lactone analogs that affect N-Ras palmitoylation.

S-Palmitoylation is a reversible post-translational lipid modification that regulates protein trafficking and signaling. The enzymatic depalmitoylation of proteins is inhibited by the beta-lactones Palmostatin M and B, which have been found to target several serine hydrolases. In efforts to better understand the mechanism of action of Palmostatin M, we describe herein the synthesis, chemical proteomic analysis, and functional characterization of analogs of this compound. We identify Palmostatin M analogs that maintain inhibitory activity in N-Ras depalmitoylation assays while displaying complementary reactivity across the serine hydrolase class as measured by activity-based protein profiling. Active Palmostatin M analogs inhibit the recently characterized ABHD17 subfamily of depalmitoylating enzymes, while sparing other candidate depalmitoylases such as LYPLA1 and LYPLA2. These findings improve our understanding of the structure-activity relationship of Palmostatin M and refine the set of serine hydrolase targets relevant to the compound's effects on N-Ras palmitoylation dynamics.

Capillary gas chromatographic determination with electron capture detector of beta-propiolactone in biological materials.

A method has been developed for the determination of beta-propiolactone by derivatizing it to the volatile N-hexyl-3-heptafluorobutanoyloxypropanamide, which can be separated and identified by a capillary CP-Sil 8 column, and detected by an electron capture detector (ECD). First, beta-propiolactone is reacted with N-hexylamine to yield N-hexyl-3-hydroxypropanamide. The fluorobutanoyl ester derivative is next prepared by using heptafluorobutyric acid anhydride in the presence of trimethylamine. The method is very sensitive, simple, and specific, and can be used to detect and quantitate residual beta-propiolactone in lyophilized biological materials. The limit of detection is 0.2 ppm beta-propiolactone in a 50 mg sample; however, because of variability at low levels, the limit of quantitation is 1 ppm. Detector response was linear for 2-500 mg beta-propiolactone. Recoveries were 98% or greater from lyophilized vaccines spiked at the 2-20 ppm level. No side products or interference peaks were observed in the derivatization reaction.

A new personal monitoring device for the detection of beta-propiolactone and other alkylating agents.

A personal monitoring badge has been developed for the detection of the direct-acting, alkylating carcinogen beta-propiolactone at atmospheric concentrations as low as 6 ppb for 24-hour and 0.6 ppm for 0.25-hour exposure. The method employs the trapping reagent p-nitrobenzyl pyridine (p-NBP) absorbed on a cellulose thin-layer chromatography (TLC) strip. Deoxyguanosine can be used in place of p-NBP, but its lower limit of detection is 60 ppb for 24-hour exposure. The authors also obtained positive results with the carcinogens bis (chloromethyl) ether, chloromethyl methyl ether, diepoxybutane, dimethylcarbamoyl chloride, ethyleneimine, and glycidaldehyde. In practice, the TLC strip is positioned in a filmbadge holder. The TLC strip monitoring badges are easy to prepare; they should encounter no resistance of personnel to their use since they are not cumbersome. Monitoring at the end of an exposure is simple and requires no expensive equipment or specialized personnel.