Characterization of Bacitracin Zinc by Matrix-Assisted Laser Desorption Ionization - Tandem Time-of-Flight Mass Spectrometry

Matrix-assisted laser desorption ionization-tandem time of flight mass spectrometry MALDI-(TOF/TOF) MS is a simple, rapid, sensitive, and high-resolution method for the characterization of polypeptides. In this article, bacitracin zinc, which is a polypeptide antibiotic, was characterized by MALDI-(TOF/TOF) MS. The mass spectrometry conditions were comprehensively investigated in this study. Nearly complete sequence coverage of bacitracin A was observed in a single tandem mass spectrum by careful adjustment of the instrumental parameters. The primary sequence of bacitracin A was analyzed by a de novo approach. The vibrations of functional groups in the infrared and electron transitions in the ultraviolet absorption spectra of bacitracin zinc were assigned and interpreted. The zinc stoichiometry was determined by inductively coupled plasma-optical emission spectrometry. This investigation of bacitracin zinc provides provides sequencing and structural characterization of this polypeptide pharmaceutical material.