Pressure-assisted tryptic digestion using a syringe.

A simple and effective digestion method was developed using a syringe. A 3 mL syringe was used to apply a pressure of 6 atm to expedite tryptic digestion. Application of a pressure of 6 atm during digestion resulted in better digestion efficiency than digestion under atmospheric pressure. The protein peaks in the matrix-assisted laser desorption/ionization mass spectra of three model proteins (cytochrome c, horse heart myoglobin, and bovine serum albumin (BSA)) completely disappeared within 30 min at 37 degrees C under a pressure of 6 atm, with greater numbers of peptides observed in 30 min pressure-assisted digestion than in overnight atmospheric pressure digestion. This is mostly due to the miscleaved peptides. Similar sequence coverages were obtained for 30 min pressure-assisted digestion and overnight atmospheric pressure digestion of the three model proteins (92% vs. 88% for cytochrome c, 100% vs. 97% for horse heart myoglobin, and 53% vs. 53% for BSA).