Protease

Tryp-N™

Tryp-N™ is a thermophilic metalloprotease with N-terminal specificity for arginine and lysine developed at Cold Spring Harbor Laboratory (CSHL). By placing basic centers of peptides (the amino terminus and side chains of K/R) in one location, b-ions predominate in MS/MS.

Benefits:

• Digestions can be completed in minutes to hours, not over night.
• Easy-to-read spectra. Tryp-N™ provides the complimentary b-ion series that can be missing from trypsin, allowing you to more easily find and specifically localize PTMs.
• Ion current is not diluted between termini (like with trypsin), enhancing sensitivity for example in MRM experiments (see below).
• Easily control digestion with the addition of EDTA for reproducible partial digests and increased sequence coverage.
• Tryp-N™ cleavage is unaffected by proline.
• It also doesn’t care about methylation.
• At higher temperatures (its T_opt is 65 °C), proteins are denatured, assisting in the analysis of difficult-to-digest proteins.
• Tryp-N™ is highly stable across a wide variety of experimental conditions including pH (5-11), buffers, ionic strength and detergents (80% active in 0.5% SDS at 50 °C!).
• At higher temperatures, endogenous enzymes are denatured and inactive: useful if pesky phosphatases or proteases interfer with your analysis.

Left: digestion is complete in 0.5 – 4 hrs, depending on temperature. Middle: Ion current is exactly inverted between trypsin and Tryp-N™. Right: Limits of detection (LODs) in MRM experiments were determined for 17 peptides of catalase produced with trypsin or Tryp-N™. The median fold increase in sensitivity was 4.5x. Average = 35.4x. 50% CI = 1.96x – 18.6x increase.