抄録
Protein identification by peptide mass fingerprinting was performed with a high performance matrix-assisted laser desorption/ionization time-of-flight mass spectrometer. The analytic capability was evaluated using two mixtures consisting of three and five tryptic digests with internal and external calibration methods. In both methods, the high mass resolving power contributed to a precise selection of monoisotopic peaks from mass spectra. In the former method, the high mass accuracy facilitated unambiguous protein identification from protein database searches. In the latter method, the high mass accuracy allowed the discrimination of the matched peptides of positive proteins from those of false-positive proteins through the difference in their mass error distributions. The mass error distribution of the matched peptides of positive proteins consisted of about 10 ppm systematic error with a random error of several ppm, whereas that of the matched peptides of false-positive proteins was random within the selected range of the peptide tolerance window.
