Structural validation of saccharomicins by high resolution and high mass accuracy fourier transform-ion cyclotron resonance-mass spectrometry and infrared multiphoton dissociation tandem mass spectrometry
- Cite this article as:
- Shi, S.D.H., Hendrickson, C.L., Marshall, A.G. et al. J Am Soc Mass Spectrom (1999) 10: 1285. doi:10.1016/S1044-0305(99)00108-7
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Exceptionally high mass resolving power and mass accuracy combined with tandem mass spectrometry (MSn) capability make Fourier transform ion cyclotron resonance mass spectrometry a powerful tool for structure verification and determination of biological macromolecules. By means of local internal calibration and electron mass correction, mass accuracy better than ±0.5 ppm was achieved for two oligosaccharide antibiotics, Saccharomicins A and B, consistent with the proposed elemental compositions based upon NMR data. High resolution and high mass accuracy MS/MS data were obtained for both oligosaccharides by use of infrared multiphoton dissociation (IRMPD) with a 40 W continuous-wave CO2 laser. The spectra were charge-state deconvolved by the “Z-score” algorithm to yield much simpler mass-only spectra. Sequences of 15 sugar residues could be confirmed from the charge state deconvolved accurate mass MS/MS spectra for Saccharomicins A and B, even without use of traditional prior permethylation. A fragment corresponding to an internal sugar loss rearrangement was observed by IRMPD and studied by collision activated dissociation MS4.