Methods are described that allow the combination of established techniques for peptide separation, paper chromatography and electrophoresis, with mass spectrometry. The development of these methods is part of an ongoing effort in the search for a methodology for the systematic utilization of mass spectrometry for the elucidation of primary structure of proteins and peptides. Peptides and ammo acids are detected on chromatograms by conversion to covalent derivatives that are also suitable for mass spectrometry. The most useful reagents for detection and derivatization of peptides reported here are dansyl chloride, N,Ndimethylaminobenzaldehyde.
N,N-dimethylaminocinnamaldehyde, and N-hy droxysuccinimido /3-naphthoate. Detection limits and mass spectra for some of these derivatives are reported.
Recently there have been some significant successes in obtaining the sequences of peptides from proteins and, in some cases, complete sequences of small proteins by mass spectrometry using various techniques. These either require sophisticated equipment or use of elaborate sample preparations (l-3). Proteins and large peptides themselves do not yield mass spectra suitable for sequence analysis. In order to employ mass spectrometry for amino acid sequence determination, it is necessary to degrade larger peptides into smaller ones, which can be converted to volatile derivatives. Generally speaking therefore, a large number of peptides would have to be generated in order to provide sufficient information for the assignment of the amino acid sequence of a protein.
The analysis of complex mixtures of peptides, without prior separation, is a difficult matter that requires exact mass, partial vaporization, and metastable-ion data (4). While a degree of success in the analysis of