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. 2009 Mar 13;284(11):6809–6817. doi: 10.1074/jbc.M805566200

FIGURE 5.

FIGURE 5.

MALDI-TOF-MS analysis of As(III) binding to a PARPzf peptide. Arsenite was incubated with a PARPzf apopeptide (Apo-PARPzf) derived from the first zinc finger for 15 min at 25 °C as described under “Experimental Procedures.” After incubation the samples were diluted 200-fold in 10 mg/ml α-Cyano-4-hydroxycinnamic acid in a 1:1 (v/v) acetonitrile/water solution, and 2 μl of each sample was deposited in duplicate on the MALDI plate, allowed to dry at room temperature, and analyzed by MALDI-TOF performed on a Applied Biosystems 4700 Proteomics Analyzer (TOF/TOF) as described under “Experimental Procedures.” A 72-Da shift was observed between 3453.8- and 3525.7-Da peaks, which corresponds to one A(III) ion binding after the release of 3 hydrogens (As(III)-PARPzf).