Solution Digestion and Protein Identification

Proteomics work almost always begins with a proteolytic digestion of intact proteins into peptides. These peptides are then analyzed by LC/MS/MS for identification. Mass spectrometry based proteomics tends to use trypsin for the vast majority of proteolysis because the peptides produced by digestion of proteins with this enzyme have very favorable properties for chromatography, electrospray ionization, and peptide fragmentation. The solution digestion (as opposed to in-gel digestion) encompasses reduction of disulfide bonds, alkylation of exposed sulfhydryls, and proteolysis with a trypsin/Lys-C mixture.

Samples may be submitted in many different forms for this service. If samples are in detergent or protease inhibitor-containing buffers, such as from homogenization or lysis, the proteins will need to be precipitated, resolubilized, and quantified using a protein assay such as the BCA. There is an additional charge for this. If proteins have already been precipitated, or if protein concentrations are already well-characterized then we can work with those samples directly. Although requirements differ vastly from experiment to experiment, for protein profiling of complex mixtures a good rule of thumb is to submit at least 50ug of protein mixture.

Solution digestion is $104 each. If a protein assay is required for samples of unknown protein concentration, that price is $115.50 per 12 samples.