Sensitivity For Protein Identification: BSA From An SDS-PAGE Gel

Serial dilutions of quantitated BSA (Pierce) were loaded onto an SDS-PAGE gel and following electrophoresis were stained using Sypro® ruby. In each case the entire band was excised and digested robotically using the procedures outlined in our protein digestionsection. Half the digest supernatant (~10 μL) was robotically loaded onto a μC18 ZipTip and eluted onto a MALDI target using the InvestigatorTM ProMS instrument. MALDI/MS data were acquired in the automated mode; spectra were averaged from 1000 (10 × 100) laser shots across the sample spot. Peaks were calibrated internally using the trypsin autolysis fragments m/z 842.5100 and 2211.1046. The following data show protein identification from 4 ng (62 fmol) and 2 ng (31 fmol) loaded on the gel, respectively.