FIGURE 2.

Effect of inhibition of MetAP on N-terminal processing of recombinant GST protein. A, ESI-MS protonation multiplicity spectra of a mixture of processed and unprocessed GST with charge states ranging from +19 to +26. B, spectra were transformed to a mass scale. The mass difference between both peaks corresponds to a methionine residue. Positions for the processed and unprocessed GST proteins are indicated by arrows. In both A and B, the spectrum using the sample in the absence of 6 is shown on the top, and the spectrum using the sample in the presence of 6 is shown on the bottom.