Syntheses and spectral properties of 2-Thiobiotin and biotin derivatives

Cleavable Linkers in Chemical Proteomics Applications

The discovery of the protein targets of small molecule probes is a crucial aspect of activity-based protein profiling and chemical biology. Mass spectrometry is the primary method for target identification, and in the last decade, cleavable linkers have become a popular strategy to facilitate protein enrichment and identification. In this chapter, we provide an overview of cleavable linkers used in chemical proteomics approaches, discuss their different chemistries, and describe how they aid in protein identification.

Characterization of N-acyl-D-biotinols by particle-beam liquid chromatography-mass spectrometry. An alternative to probe mass spectrometry for thermally labile samples

In the course of preparing biotin-labeled nucleic acid probes, it was necessary to verify structures of intermediate N-acyl derivatives of biotinol. Characterization by mass spectrometry (MS) involved use of particle-beam liquid chromatography (LC)-mass spectrometry MS to supplement standard heated-solids probe techniques. The probe data for a sample of N-toluoylbiotinol indicated it to be a mixture of mono- and di-toluoylbiotinols which was inconsistent with other analytical information. Analysis of the same sample by LC-MS on a reversed-phase column with a water-acetonitrile gradient showed a single major peak with spectrum consistent with that for the monotoluoyl species. These results suggested that a thermal transacylation reaction might be occurring in the probe during heating prior to volatilization and ionization. This was confirmed by heating the sample to 200 degrees C and then repeating the LC-MS analysis to find peaks now present for biotinol and ditoluoylbiotinol as well as the starting material. These results demonstrate the value of particle-beam LC-MS as a technique for obtaining electron-impact mass spectra of thermally sensitive compounds.