Both phthiocerol/phthiodiolone dimycocerosate (PDIM) and phenolic glycolipids are abundant virulent lipids in the cell wall of various pathogenic mycobacteria, which can synthesize a wide range of complex high-molecular-mass lipids. In this article, we describe linear ion-trap MSn mass spectrometric approach for structural study of PDIMs, which were desorbed as the [M + Li]+ and [M + NH4]+ ions by ESI. We also applied charge-switch strategy to convert the mycocerosic acid substituents to their N-(4-aminomethylphenyl) pyridinium (AMPP) derivatives and analyzed them as M + ions, following alkaline hydrolysis of the PDIM to release mycocerosic acids.
