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. Author manuscript; available in PMC: 2007 Jun 15.
Published in final edited form as: Biochemistry. 2006 Nov 28;45(47):14223–14231. doi: 10.1021/bi061677n

FIGURE 7.

FIGURE 7

MALDI-TOF mass spectra of DEPC modification of the synthetic His-rich decapeptide before (A) and after (B) Cu2+ incubation. Integers over the peaks represent the calculated number of carbethoxylations. Note that all eight of the His residues and two other functionalities appear to be monocarbethoxylated DEPC (A, i), which prevents any Cu2+ binding that can be detected by MALDI-TOF (A, ii). Conversely, Cu2+ binding prior to DEPC exposure abolishes monocarbethoxylation by any peptide functionality (B, i and ii).