Infrared-assisted proteolysis using trypsin-immobilized silica microspheres for peptide mapping

A novel proteolysis approach was developed by using infrared (I R) radiation and trypsin-immobilized silica microspheres. Protein solutions containing trypsin-immobilized microspheres in sealed transparent Eppendorf tubes were allowed to digest under an I R lamp at 37 degrees C. The feasibility and performance of the present proteolysis approach were demonstrated by the digestion of BSA and cytochrome c (Cyt-c) and the digestion time was significantly reduced to 5 min. The obtained digests were identified by MALDI-TOF-MS with the sequence coverages of 54% (BSA) and 83% (Cyt-c) that were better than those obtained by conventional in-solution tryptic digestion. The suitability of the new digestion approach to complex proteins was demonstrated by digesting human serum. The present proteolysis strategy is simple and efficient and will find a wide range of application in protein identification.