A MULTIDIMENSIONAL APPROACH TO PROTEIN CHARACTERIZATION

When mass spectrometry (MS) is used to study protein primary structure , it is used in a ''static'' mode. That is, the information is derived from a single MS or MS-MS spectrum. Information about more complex pr otein structure or protein interactions can also be gained via MS. If a series of mass spectra is collected as something else in the experim ent is changing, we increase the ''dimensionaiity'' of the MS data. Fo r example, measuring mass spectra as a function of time after exposure of a protein to deuterated solvents can provide information about pro tein structure. Likewise, by measuring mass spectra of a protein as th e concentration of a binding ligand is changed, one can infer the stoi chiometry of the complex. Another important, but fundamentally differe nt way of increasing the dimensionality of mass spectral data is by co upling the mass spectrometer to a one- or two-dimensional separation t echnique.