Sequencing of long and short BHMT forms by mass spectrometry. Sections corresponding to the BHMT bands p45 and p10 (from LP-IEF fraction no. 20; cf. Fig. 2) were excised from SDS-PAGE gels, minced and trypsinized, and the peptide mixtures were analyzed by ESI-IT-MS/MS or MALDI-TOF MS. (A) p45 sequence deduced from combined data; (B) p10 sequence deduced from combined data. Modified lysine residues marked by asterisk. No N-terminal peptide was recovered from p45 and no C-terminal peptide from p10. (C) ESI-IT spectrum of the peptide underlined in (B); (D), MALDI-TOF spectrum of p10. The masses of the four identifying peptides are indicated; the data provided by the SwissProt database, using the Protein Prospector search software, are shown in facsimile below.