[A simple protein in-gel digest method compatible with mass spectrometry analysis].

A simple protein in-gel digest method compatible with MALDI-TOF MS analysis was developed from the previously reported protocols with the following modifications. (1) The washing step was intensified by increasing the volume of distilled water and prolonging the vortex time. (2) Trypsin was acidified to improve the enzyme activity. (3) A Ca(2+) free pre-digest solution was used to reduce the trypsin auto cleavage. (4) The procedure of removal of salts and SDS was cancelled. (5) The digest was directly used to perform MALDI-TOF MS analysis. The compared results of this method with a latest reported protocol demonstrated that the method could efficiently reduce the peptide loss, provide more information for MS analysis, and consequently make the protein identification more reliable.