Metal-chelating plastic MALDI (pMALDI) chips for the enhancement of phosphorylated-peptide/protein signals

J Proteome Res. 2007 Sep;6(9):3842-8. doi: 10.1021/pr070243r. Epub 2007 Jul 27.

Abstract

A disposable polymeric pMALDI array with a universal metal cation-chelatable surface for pretreatment/signal enhancement of phosphoproteins and/or phosphopeptides in complex samples was developed. Acrylic acid N-hydroxysuccinimide ester and methyl methacrylate monomers were copolymerized in thin layer molds in a 1:13.3 molar ratio and subsequently treated with Nalpha,Nalpha-bis(carboxymethyl)-l-lysine to obtain a structured planar MALDI array. The prepared NTA pMALDI chip array was activated with metal cations (e.g., Ga(III), Ni(II)), and the selectivities for phosphopeptides (e.g., trypsin-digested alpha-casein (alpha-Cas), and phospho-angiotensin II (p-Ang)) were evaluated using MALDI-TOF/MS. The highest selectivity for proteins was observed for the Ni(II)-NTA chip. The p-Ang was enriched in the presence of BSA tryptic peptides ca. 5 times and represented the major peak after sample adsorption/washing on Ga(III)-NTA chip. The performance of the Ga(III)-chip, tested on alpha-Cas tryptic digest, is fully comparable to commercial systems. Additionally, higher MW peptides and limited methionine oxidation were observed with the chip. A combination of selective absorption of phosphoproteins on Ni(II)-chips and the further enrichment of digested phosphopeptides on the Ga(III)-chip can prove to be very useful for fast identification of unknown proteins using MALDI-TOF/MS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption
  • Angiotensin II / chemistry
  • Gallium / chemistry
  • Humans
  • Mass Spectrometry / methods
  • Peptide Mapping
  • Peptides / chemistry*
  • Phosphopeptides
  • Phosphoproteins / chemistry
  • Phosphorylation
  • Polymers / chemistry
  • Proteins / chemistry*
  • Proteomics / instrumentation*
  • Proteomics / methods*
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Substances

  • Peptides
  • Phosphopeptides
  • Phosphoproteins
  • Polymers
  • Proteins
  • Angiotensin II
  • Gallium