Use of vapor-phase acid hydrolysis for mass spectrometric peptide mapping and protein identification

A method for mass spectrometric peptide mapping was developed, based on hyd rolysis of a solid protein by acid vapor followed by mass spectrometric ana lysis of the cleavage products, The method is applicable to lyophilized sam ples as well as proteins present in gels after separation by SDS-PAGE. The cleavage specificity was established using a number of standard proteins. T hree different types of cleavages were observed: specific internal backbone cleavages at Asp, Ser, Thr, and Gly and N- and C-terminal sequence ladders , On the basis of the observed cleavage characteristics, a strategy for pro tein identification based on the peptide mass maps was developed. The ident ification strategy utilizes the specific internal backbone cleavages as wel l as the partial sequence information, obtained from the sequence ladders.