MALDI-MS of Protein Complexes and Interactions
Our laboratory was the first to demonstrate that specific protein-protein interactions could be preserved on conventional MALDI targets during the ionisation of non-binding components providing an indirect means with which to probe protein interactions.
This method of studying protein complexes by MALDI requires a comparison of a control
(no binding partner) MALDI spectrum with that of the partner-treated mixture.
The binding protein/peptide(s) is/are determined from the decrease in absolute area or intensity across both spectra relative to a nonbinding peptide or protein signal. The approach has been renamed by others as "intensity fading" MALDI-MS.
First reported in 1999 for the protein lysozyme, it was subsequently applied in the same year to a biological mixture in the form of protein antigens of the influenza virus. It has since been applied to gel-recovered antigens (2006, 2007) and applied in time-course experiments (2008) to measure the relative rates of binding. A computer algorithm to interpret such MALDI spectral pairs has also been developed (2007).
See Chapter 2 of the book "Mass Spectrometry of Protein Interactions" for a full description of these events and the development of MALDI-MS to study protein complexes.
Original relevant references:
Kiselar JG, Downard KM (1999) Direct identification of protein epitopes by mass spectrometry without immobilization of antibody and isolation of antibody–peptide complexes, Anal. Chem., 71: 1792–1799.
Kiselar JG, Downard KM (1999) Antigenic Surveillance of the Influenza Virus by Mass Spectrometry, Biochemistry 43: 14185-14191.
Kiselar J.G., Downard K.M. (2000) Preservation and Detection of Specific Antibody-Peptide
Complexes by Matrix-assisted Laser Desorption Ionization Mass Spectrometry, J. Am.Soc Mass Spectrom., 11: 746-750.
Morrissey B, Downard KM (2006) A Proteomics Approach to Survey the Antigenicity of the Influenza Virus by Mass Spectrometry, Proteomics, 6: 2034-2041.
Morrissey B, Streamer M, Downard KM (2007) Antigenic Characterisation of H3N2 subtypes of the Influenza Virus by Mass Spectrometry, J. Virol. Methods, 145: 106–114.
Ho JWK, Morrissey B, Downard KM (2007) A Computer Algorithm for the Identification of Protein Interactions from the Spectra of Masses (PRISM), J. Am. Soc. Mass Spectrom., 18: 563–566.
Morrissey B, Downard KM (2008) Kinetics of Antigen-Antibody Interactions Employing a MALDI Mass Spectrometry Immunoassay, Anal. Chem., 80: 7720-7726.
