DEVELOPMENT OF A 3-DIMENSIONAL TOPOGRAPHIC MAP DISPLAY FOR CAPILLARY ELECTROPHORESIS MASS-SPECTROMETRY WITH AN ION TRAP REFLECTRON TIME-OF-FLIGHT MASS-SPECTROMETER DETECTOR - APPLICATIONS TO TRYPTIC DIGESTS OFISOFORMS OF MYELIN BASIC-PROTEIN/

A three-dimensional (3-D) contour map format has been developed to dis play the large amount of data continuously collected throughout an on- line capillary separation using an ion trap storage/reflectron time-of -flight detector (IT/reTOF). The resulting data are displayed on a sin gle computer screen with a mass-to-charge ratio value-elution time-int ensity representation. The intensity of various components is represen ted by 16 different colors so that the mass-to-charge ratio value, the elution time, and the intensity can be conveniently determined for ea ch component. In addition, the mass spectrum and total ion chromatogra m or total ion electropherogram (TIE) are shown on the same screen as the 3-D map that enables the correlation of a single spot in the 3-D m ap to the peaks in the TIE and the corresponding mass spectrum. The 3- D map has been used to identify various posttranslational modification sites of bovine myelin basic protein charge isomers, where the datafi les of tryptic digests of proteins analyzed by capillary electrophores is/mass spectrometry were processed by this software and a comparison could be performed among the isoforms. The feature of in-screen integr ation over both the separation domain and the mass domain makes the ac quisition of the selected ion chromatogram very convenient and greatly improves the ability to detect modified components present in low amo unts. (C) 1998 American Society for Mass Spectrometry.