Top-down proteomics

Top-down proteomics is a method of protein identification that uses an ion trapping mass spectrometer to store an isolated protein ion for mass measurement and tandem mass spectrometry analysis. Top-down proteomics is capable of identifying and quantitating unique proteoforms through the analysis of intact proteins. The name is derived from the similar approach to DNA sequencing. Proteins are typically ionized by electrospray ionization and trapped in a Fourier transform ion cyclotron resonance (Penning trap) or quadrupole ion trap (Paul trap) mass spectrometer. Fragmentation for tandem mass spectrometry is accomplished by electron-capture dissociation or electron-transfer dissociation. Effective fractionation is critical for sample handling before mass-spectrometry-based proteomics. Proteome analysis routinely involves digesting intact proteins followed by inferred protein identification using mass spectrometry. Top-down proteomics interrogates protein structure through measurement of an intact mass followed by direct ion dissociation in the gas phase.

Currently the most advanced instrument used to map proteoforms is the Thermo Scientific Orbitrap Fusion Lumos Tribrid mass spectrometer. This high-performance instrument is able to give a quantitative analysis of proteoforms, identify them, and deeply characterize them with tandem MS/MS.

Study One: Quantitation and Identification of Thousands of Human Proteoforms below 30 kDa

Study Two: Combining high-throughput MALDI-TOF mass spectrometry and isoelectric focusing gel electrophoresis for virtual 2D gel-based proteomics

...
Wikipedia