A small-scale method for the preparation of plant N-linked glycans from soluble proteins for analysis by MALDI-TOF mass spectrometry

Plant Physiol Biochem. 2009 Feb;47(2):160-6. doi: 10.1016/j.plaphy.2008.10.005. Epub 2008 Oct 26.

Abstract

The use of plants as production hosts for recombinant glycoproteins, which is rapidly developing, requires methods for fast and reliable analysis of plant N-linked glycans. This study describes a simple small-scale method for the preparation of N-linked glycans from soluble plant protein and analysis thereof by matrix assisted laser desorption ionisation time of flight mass spectrometry (MALDI-TOF MS). Concentration and protease digestion of plant protein as well as deglycosylation is carried out in a single concentrator unit without the need for intermittent purification to minimize adsorptive loss and to facilitate handling. Plant protein is concentrated in a unit with a 5kDa cutoff, and after buffer exchange, pepsin (EC 3.4.23.1) digestion is carried out in the concentrator overnight to obtain peptides as substrates for deglycosylation. Deglycosylation is carried out with peptide-N-glycosidase A (PNGase A; EC 3.5.1.52) for 24h. Released N-glycans are purified using reverse-phase and cation exchange chromatography micro-columns for removal of peptides and desalting. N-Glycans are directly analyzed by MALDI-TOF MS without derivatization. The method for isolation of N-glycans is compatible with secreted proteins from cell culture supernatant as well as with soluble protein extracts from leaf tissue. As little as 5mug of plant glycoprotein is sufficient for N-glycan preparation for MALDI-TOF MS analysis using this method.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Glycoproteins / isolation & purification*
  • Glycosylation
  • Humans
  • Nicotiana / chemistry
  • Nitrogen
  • Plant Proteins / isolation & purification*
  • Polysaccharides / isolation & purification*
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*

Substances

  • Glycoproteins
  • Plant Proteins
  • Polysaccharides
  • Nitrogen