Peptide Imaging: Maximizing Peptide Yield, Optimization of the "Peptide Mass Fingerprint"

In Matrix Assisted Laser Desorption Ionization Mass Spectrometry Imaging (MALDI-MSI), identification of observed proteins remains a challenge primarily due to the drop in sensitivity of time-of-flight (TOF) mass spectrometers beyond the mass range of 25-35 kDa (Francese et al. High Throughput Screen 12: 156-174, 2009) and inadequate mass resolving power at those molecular weights. To counteract this, a bottom-up proteomic approach is often employed. Proteolysis digests proteins into smaller peptide fragments, typically between 500 and 3000 Da which are easier to detect with a higher mass accuracy. Here, we describe the addition of a MS-compatible detergent to the endopeptidase trypsin, to enhance in situ proteolysis efficiency and peptide intensity.