Determination of Bioactive Peptide Molecular Mass Using Electrospray and MatrixAssisted Laser Desorption Ionization Mass Spectrometry

摘要

Twelve bioactive peptides, ranging in molecular masses from 600 and 4500 u, wereselected for ESI-MS and MALDI-TOF-MS analysis in order to assess the spectrometric data that could be accessed for rapid CB screening purposes. Monoisotopic molecular mass data were obtained for all the peptides by ESI-MS with a tri-focusing magnetic sector instrument in the continuum mode using resolutions between 3000 and 6000 (10% valley definition). MALDI-TOF-MS data were collected with an instrument that featured a four-plate source design, pulsed ion extraction for time-lag focusing, and a 1-m linear flight tube. High resolution mass measurements with the tri-focusing magnetic sector instrument were the most accurate. Errors between theoretical and calculated monoisotopic (or average) molecular mass were in the 0.3 to 18 ppm and 10 to 96 ppm range during ESI-MS and MALDI-TOF-MS analysis, respectively. ESI-MS data may be acquired with as little as 1 to 10 pmoles of peptide at resolutions of 2000 to 3000 (10% valley definition) with the tri-focussing magnetic sector instrument. The MALDI-TOF-MS instrument described offered improved sensitivities with only 0.1 to 1 pmole of peptide being required. In both cases analyses times were rapid, with analyses taking 2 to 5 minutes per sample. Both ionization techniques, ESI and MALDI, would be suitable for rapid molecular mass screening purposes.