文摘
A new strategy for identifying proteins in sequence databases by MALDI-MS peptide mapping is reported. Thestrategy corrects for systematic deviations of determinedpeptide molecular masses using information contained inthe opened database and thereby renders unnecessaryinternal spectrum calibration. As a result, data acquisitionis simplified and less error prone. Performance of the newstrategy is demonstrated by identification of a set ofrecombinant, human cDNA expression products as wellas native proteins isolated from crude mouse brainextracts by 2-D electrophoresis. Using one set of calibration constants for the mass spectrometric analyses, 20proteins were identified without applying any molecularweight restrictions, which was not possible without datacorrection. A sequence database search program has beenwritten that performs all necessary calculations automatically, access to which will be provided to the scientificcommunity in the Internet.