Tumor suppressor protein p53 is often expressed as a fusion protein with glutathione-S-transferase (GST). The sensitive determination of GST in p53 samples is thus necessary. We propose a method for the determination of traces of GST in the p53 C-terminus based on the constant current chronopotentiometric stripping analysis (CPSA) with hanging mercury drop electrode (HMDE). GST produces a catalytic signal in cobalt-containing solutions due to cysteine residues. A large excess of the C-terminus does interfere with the determination because of the lack of cysteines in the molecule. This method is simple and very sensitive and is capable of detecting <1% GST in the p53 sample.

Institute of Biophysics Academy of Sciences of the Czech Republic Královopolská 135 CZ 612 65 Brno Czech Republic

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