Bottom-up proteomics

<p>Bottom-up proteomics is a common method to identify proteins and characterize their amino acid sequences and <a href="/facts/Post-translational_modification/KMUayTIc">post-translational modifications</a> by <a href="/facts/Proteolysis/GtQdv6J7">proteolytic digestion</a> of proteins prior to analysis by <a href="/facts/Mass_spectrometry/RH5WBHJ2">mass spectrometry</a>. 
BUP techniques can be an alternative to <a href="/facts/Matrix-assisted_laser_desorption%2fionization/nBBXfb2Q">Maldi-Tof MS</a> approaches, as they allow the identification of bacterial strains and the characterization of potential resistance and virulence factors in a single run.
The major alternative workflow used in <a href="/facts/Proteomics/3aqQ1tFh">proteomics</a> is called <a href="/facts/Top-down_proteomics/xQNPy5Ff">top-down proteomics</a> where intact proteins are purified prior to digestion and/or fragmentation either within the mass spectrometer or by 2D electrophoresis. Essentially, bottom-up proteomics is a relatively simple and reliable means of determining the protein make-up of a given sample of cells, tissues, etc. 
</p><p>In bottom-up proteomics, the crude protein extract is enzymatically digested, followed by one or more dimensions of separation of the peptides by <a href="/facts/High_performance_liquid_chromatography/UNT9jPp0">liquid chromatography</a> coupled to mass spectrometry, a technique known as <a href="/facts/Shotgun_proteomics/AVlHCaqf">shotgun proteomics</a>. By comparing the masses of the proteolytic peptides or their <a href="/facts/Tandem_mass_spectrometry/otT5Q9tY">tandem mass spectra</a> with those predicted from a sequence database or annotated peptide spectral in a <a href="/facts/Peptide_Spectral_Library/6FPHNz2p">peptide spectral library</a>, peptides can be identified and multiple peptide identifications assembled into a protein identification.
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Bottom-up proteomics open-in-new

Bottom-up proteomics