title: Correlated matrix-assisted laser desorption/ionization mass spectrometry and fluorescent imaging of photocleavable peptide-coded random bead-arrays.
abstract: BACKGROUND
  Rapidly performing global proteomic screens is an important goal in the post-genomic era. Correlated matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and fluorescent imaging of photocleavable peptide-coded random bead-arrays was evaluated as a critical step in a new method for proteomic screening that combines many of the advantages of MS with fluorescence-based microarrays.
  
  
  METHODS
  Small peptide-coded model bead libraries containing up to 20 different bead species were constructed by attaching peptides to 30-34 µm diameter glass, agarose or TentaGel® beads using photocleavable biotin or a custom-designed photocleavable linker. The peptide-coded bead libraries were randomly arrayed into custom gold-coated micro-well plates with 45 µm diameter wells and subjected to fluorescence and MALDI mass spectrometric imaging (MALDI-MSI).
  
  
  RESULTS
  Photocleavable mass-tags from individual beads in these libraries were spatially localized as ~65 µm spots using MALDI-MSI with high sensitivity and mass resolution. Fluorescently tagged beads were identified and correlated with their matching photocleavable mass-tags by comparing the fluorescence and MALDI-MS images of the same bead-array. Post-translational modification of the peptide Kemptide was also detected on individual beads in a photocleavable peptide-coded bead-array by MALDI-MSI alone, after exposure of the beads to protein kinase A (PKA).
  
  
  CONCLUSIONS
  Correlated MALDI-MS and fluorescent imaging of photocleavable peptide-coded random bead-arrays can provide a basis for performing global proteomic screening.
authors.affiliation: AmberGen, Incorporated, 313 Pleasant Street, Watertown, MA, 02472, USA.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Lim
authors.forename: Ziying
authors.initials: Z
authors.lastname: Liu
authors.forename: Karen I
authors.initials: KI
authors.lastname: Braunschweiger
authors.forename: Amany
authors.initials: A
authors.lastname: Awad
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Rothschild
mesh_terms: D046228:Microarray Analysis / Q000295:instrumentation / Q000379:methods; D008863:Microspheres; D008958:Models, Molecular; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D010766:Phosphorylation; D010782:Photolysis; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D019809:Streptavidin
chemical_list: D019151:Peptide Library; D010455:Peptides; D019809:Streptavidin