Journal of the American Society for Mass Spectrometry

, Volume 15, Issue 12, pp 1874–1884

Ion soft-landing into liquids: Protein identification, separation, and purification with retention of biological activity

  • Bogdan Gologan
  • Zoltán Takáts
  • Jormarie Alvarez
  • Justin M. Wiseman
  • Nari Talaty
  • Zheng Ouyang
  • R. Graham Cooks
Articles

DOI: 10.1016/j.jasms.2004.09.005

Cite this article as:
Gologan, B., Takáts, Z., Alvarez, J. et al. J Am Soc Mass Spectrom (2004) 15: 1874. doi:10.1016/j.jasms.2004.09.005

Abstract

Protein ions, after mass spectrometric separation, can be soft-landed into liquid surfaces with preservation of their native structures. Retention of biological activity is strongly favored in glycerol-based surfaces but not in self-assembled monolayer solid surfaces. Soft-landing efficiency for multiply-charged hexokinase ions was found to be some four times higher for a glycerol/fructose liquid surface than for a fluorinated self-assembled monolayer surface. Soft-landing into liquid surfaces is also shown to allow (1) protein purification, (2) on-surface identification of the soft-landed material using MALDI, and (3) protein identification by in-surface tryptic digestion. Pure lysozyme was successfully isolated from different mixtures including an oxidized, partially decomposed batch of the protein and a partial tryptic digest. Liquid glycerol/carbohydrate mixtures could be used directly to record MALDI spectra on the soft-landed compounds provided they were fortified in advance with traditional MALDI matrices such as p-nitroaniline and α-cyano-4-hydroxycinnamic acid. Various proteins were soft-landed and detected on-target using these types of liquid surface. Soft-landing of multiply-charged lysozyme ions onto fluorinated self-assembled monolayer surfaces was found to occur with a limited amount of neutralization, and trapped multiply-charged ions could be desorbed from the surface by laser desorption. Initial data is shown for a new approach to protein identification that combines top-down and bottom-up approaches by utilizing protein ion soft-landing from a protein mixture, followed by tryptic digestion of the landed material and detection of characteristic tryptic fragments by MALDI.

Copyright information

© American Society for Mass Spectrometry 2004

Authors and Affiliations

  • Bogdan Gologan
    • 1
  • Zoltán Takáts
    • 1
  • Jormarie Alvarez
    • 1
  • Justin M. Wiseman
    • 1
  • Nari Talaty
    • 1
  • Zheng Ouyang
    • 1
  • R. Graham Cooks
    • 1
  1. 1.Department of ChemistryPurdue UniversityWest LafayetteUSA

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