2-DIMENSIONAL MASS-SPECTROMETRY OF BIOMOLECULES AT THE SUBFEMTOMOLE LEVEL

Multiple dimensions of unique molecular structure information can now be obtained from proteins and DNA using mass spectrometry. Less than 1 0(-16) mol of the active major histocompatibility complex signaling pe ptide in a mixture of thousands can be identified. For large proteins (>40 kDa), the high resolving power (>10(5)) and 10(-17) mol sensitivi ty of Fourier-transform mass spectrometry provide exact molecular weig ht values (+/- 1 or 2 Da) for mixture components, indicating errors or modifications compared with the predicted DNA sequence. Selecting a s pecific molecular species, its two-dimensional spectrum indicates the part of the molecule that is modified; a three-dimensional spectrum of that fragment further isolates the modification site.