Trypsin is a serine protease that specifically cleaves at the carboxylic side of lysine and arginine residues. The stringent specificity of trypsin is essential for characterizing proteins using mass spectrometry. We provide a variety of trypsin formats. In all cases lysine residues were modified by reductive methylation, yielding a highly active and stable molecule that is extremely resistant to autolytic digestion. The specificity of the purified trypsin is further improved by TPCK treatment, which inactivates chymotrypsin. (Figure 1).
Figure 1. Schematic overview of protocol for generating modified trypsin.
Sequencing Grade Modified Trypsin is porcine trypsin modified by reductive methylation, rendering it resistant to proteolytic digestion and treated with TPCK to inactivate chymotrypsin. Trypsin is often used for in-gel or in-solution digestion of proteins. The digested peptides are purified and concentrated, then analyzed by mass spectrometry to determine their molecular weights. Database searches then can be performed, using the mass of the peptides to identify the protein(s) resolved on the gel (Figure 2).
Trypsin Gold, Mass Spectrometry Grade, is manufactured to provide maximum specificity. The treated trypsin is purified by affinity chromatography and lyophilized to yield Trypsin Gold, Mass Spectrometry Grade. Each lot of quality-tested Trypsin Gold is qualified for use with in-gel digestion and mass spectrometric analysis.
Immobilized Trypsin provides a fast and convenient method for digesting a range of concentrations of purified protein or complex protein mixtures. Immobilized Trypsin is easily removed from the digested peptide solution using a spin column because the trypsin does not pass though the column frit (Figure 4).