Measuring proteins with mass spectrometry
Many cellular processes are regulated by precise amounts of specific protein complexes, ligands, or enzymes. Protein stoichiometry aims to measure the exact amounts of the individual components of these protein complexes, which is a requirement for fully understanding their overall function.
Thermo Scientific Orbitrap MS solutions enable high-resolution, extended mass range, and accurate mass solutions for the analysis of protein complex topology and stoichiometry.
MS techniques used for protein stoichiometry
Quantitative peptide‐based MS approaches can be used to determine protein stoichiometries in protein complexes, the first step in elucidating protein complex structures. Alternatively, targeted approaches with known amounts of isotopically labeled standards of the protein/peptide in question can be spiked in to gain an accurate measurement of these protein complexes.
The direct introduction of protein complexes in their native biological state enables analysis of protein-protein and protein-ligand complexes. Mass measurements coupled to protein identifications confirm the precise stoichiometry of these complexes. This information is the crucial first step in protein complex structure determination.
Crosslinking mass spectrometry (XL-MS) can be used to determine the binding stoichiometry of individual protein complexes. This is advantageous when dealing with labile proteins and protein complexes. Typically, zero length or non-specific crosslinkers are used to preserve the interacting partners for measurement of protein stoichiometry.