Protein Sequencing Tools | Protein Research

sequencing grade protease enzymes

MSG-Trypsin™
Trypsin is a serine endopeptidase that specifically cleaves peptide bonds on the carboxy side of s-aminoethyl cysteine, arginine and lysine residues. Typically there is little or no cleavage at arginyl-proline and lysyl-proline bonds.

Trypsin undergoes autolysis, producing trypsin fragments that interfere with sequence analysis. G-Biosciences' MSG-Trypsin™ is a chemically modified trypsin that is enzymatically active and yet resistant to autolysis. MSG-Trypsin™ is methylated, TPCK treated and quality tested for mass spectrometry.

Unlike other trypsin preparations, MSG-Trypsin™ is highly stable, maintaining its activity in severe denaturing buffers and as a result, is shipped without requiring dry ice and can be stored for a long period without any loss of activity.

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SG-Arginine-C™
SG-Arginine-C™ endopeptidase (Clostripain, from C. histolyticum) specifically hydrolyzes the carboxy peptide bond of Arginine. SG-Arginine-C™ has been modified chemically by a propriety process to render the enzyme resistant to autolysis and stabilize enzymatic activity. In addition, as a sulfhydryl enzyme, SG-Arginine-C™ is susceptible to inactivation by oxidation and as a result requires reducing agents for protection. The enzyme also requires calcium ion for maximal activity. A special reconstitution buffer is supplied, which contains reducing agents and activators to maintain enzyme activity.

SG-Arginine-C™ is supplied lyophilized in an activated form in 5μg vials and can be reconstituted to a concentration of 0.25μg/ml by addition of 20μl per vial of the supplied reaction buffer. For fragmentation the enzyme is added to the sample protein in a ratio of 1:100 to 1:20 (enzyme to protein, by weight)
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SG-Aspartic-N™
SG-Aspartic-N™ is a metallo-endoproteinase, isolated from a mutant strain of Pseudomonas fragi that specifically hydrolyzes peptide bonds on the N-terminal side of aspartic acid and cysteine residues. It has an optimal activity at pH6.5-8.0.

SG-Aspartic-N™ is subjected to extensive purification to remove contaminating proteases, which could affect the specificity of the digestion process. The highly purified SG-Aspartic-N™ is subsequently modified chemically, resulting in increased resistance to autolysis and improved stability. For protein fragmentation the enzyme is added to the protein to be digested at a ratio of 1:100 to 1:50, by weight in a standard digestion buffer (50mM Tris.HCl, pH 8.0, 50mM sodium phosphate pH 8.0, or 50mM (NH₄)HCO₃). Ideally incubate at 25-30°C for 2 to 6 hours; but can be extended to 24 hours if required. For overnight incubation a ratio of 1:100, enzyme to protein is adequate for most proteins.
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SG-Chymotrypsin™
SG-Chymotrypsin™ is a serine endopeptidase, which predominantly cleaves peptide bonds on the carboxy side of tyrosine, phenylalanine and tryptophan. In addition, chymotrypsin has a low catalytic activity against the carboxy side of leucine, methionine, alanine, aspartic and glutamic acids. It is therefore recommended to always use the shortest digestion time possible.

SG-Chymotrypsin™ is first treated with TLCK to inhibit trypsin that may be present and then subjected to an extensive purification process to remove contaminating protease and chymotryptic autolysis by-products. The highly purified enzyme is then chemically modified to increase its resistance to autolysis and stability.

For protein digestion SG-Chymotrypsin™ is added to the protein at a ratio of 1:200 to1:50, by weight, in a standard digestion buffer. Incubate at 25-30°C for 1 to 10 hours, but can be extended to 24 hours, due tothe extended life of the SG-Chymotrypsin™. We recommend choosing a ratio of enzyme to protein that allows for the shortest incubation time possible. This will reduce or eliminate the catalyzed hydrolysis of peptide bonds with non-aromatic amino acid residues.
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SG-Glutamic-C™
SG-Glutamic-C™ is a serine endopeptidase, from S. aureus V8, that is highly specific for the cleavage of peptide bonds at the carboxy side of either aspartic or glutamic acid, depending on the buffer used. In Tris-HCl buffer, in particular in the absence of phosphate ions, the enzyme is specific for the glutamyl site. Recommended buffers for fragmentation of proteins using this enzyme are 50mM Tris-HCI, pH 8.0 or bicarbonate buffer. Highly purified preparations of SG-Glutamic-C™ are chemically modified makingthe enzyme both resistant to autolysis and stabilizes its enzymatic activity.

SG-Glutamic-C™ is supplied lyophilized in 10μg vials. The enzyme is typically reconstituted to a concentration of 0.5μg/ml and commonly used at a ratio of 1:100 to 1:20 (enzyme to protein, by weight) in a standard digestion buffer.
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SG-Lysine-C™
SG-Lysine-C™ endopeptidase, from Lysobacter enzymogenes, is a serine protease highly specific in cleaving peptide bonds at the carboxy side of lysine. Highly purified preparations of SG-Lysine-C™ are chemically modified making the enzyme resistant to autolysis and stabilizing its enzymatic activity.

SG-Lysine-C™ is supplied lyophilized in 5μg vials. The enzyme is typically reconstituted to a concentration of 0.25μg/ml. For fragmentation, the enzyme is added to the sample protein in a ratio of 1:100 to 1:20 (enzyme to protein, by weight) in a standard digestion buffer.
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