Characterization, stoichiometry, and stability of salivary protein–tannin complexes by ESI-MS and ESI-MS/MS

  • Francis Canon
  • Franck Paté
  • Emmanuelle Meudec
  • Thérèse Marlin
  • Véronique Cheynier
  • Alexandre Giuliani
  • Pascale Sarni-Manchado
Original Paper

DOI: 10.1007/s00216-009-3180-3

Cite this article as:
Canon, F., Paté, F., Meudec, E. et al. Anal Bioanal Chem (2009) 395: 2535. doi:10.1007/s00216-009-3180-3

Abstract

Numerous protein–polyphenol interactions occur in biological and food domains particularly involving proline-rich proteins, which are representative of the intrinsically unstructured protein group (IUP). Noncovalent protein–ligand complexes are readily detected by electrospray ionization mass spectrometry (ESI-MS), which also gives access to ligand binding stoichiometry. Surprisingly, the study of interactions between polyphenolic molecules and proteins is still an area where ESI-MS has poorly benefited, whereas it has been extensively applied to the detection of noncovalent complexes. Electrospray ionization mass spectrometry has been applied to the detection and the characterization of the complexes formed between tannins and a human salivary proline-rich protein (PRP), namely IB5. The study of the complex stability was achieved by low-energy collision-induced dissociation (CID) measurements, which are commonly implemented using triple quadrupole, hybrid quadrupole time-of-flight, or ion trap instruments. Complexes composed of IB5 bound to a model polyphenol EgCG have been detected by ESI-MS and further analyzed by MS/MS. Mild ESI interface conditions allowed us to observe intact noncovalent PRP–tannin complexes with stoichiometries ranging from 1:1 to 1:5. Thus, ESI-MS shows its efficiency for (1) the study of PRP–tannin interactions, (2) the determination of stoichiometry, and (3) the study of complex stability. We were able to establish unambiguously both their stoichiometries and their overall subunit architecture via tandem mass spectrometry and solution disruption experiments. Our results prove that IB5·EgCG complexes are maintained intact in the gas phase.

Figure

Schematic illustrating the interaction between IB5 and EgCG, leading to IB5·EgCG complexes that remain intact in the gas phase during ESI-MS analysis. This system provides a model of biological interest with regards to astringency

Keywords

Polyphenol Interaction Proline-rich protein Saliva Astringency IUP 

Abbreviations

CID

collision-induced dissociation

EgCG

epigallocatechin gallate

ESI

electrospray ionization

IUP

intrinsically unstructured protein

MS

mass spectrometry

MS/MS

tandem mass spectrometry

PRP

proline-rich protein

Q-TOF

quadrupole/time-of-flight

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Francis Canon
    • 1
  • Franck Paté
    • 1
  • Emmanuelle Meudec
    • 1
  • Thérèse Marlin
    • 1
  • Véronique Cheynier
    • 1
  • Alexandre Giuliani
    • 2
    • 3
  • Pascale Sarni-Manchado
    • 1
  1. 1.UMR 1083 Sciences Pour l’Oenologie, Polyphenol Interaction Research GroupINRAMontpellierFrance
  2. 2.DISCO beamlineSynchrotron Soleil, l’Orme des MerisiersGif sur YvetteFrance
  3. 3.CEPIAINRANantesFrance

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