Reduction of a platinum(IV) prodrug model by sulfur containing biological reductants: computational mechanistic elucidation

A PtIV prodrug needs to be reduced to PtII by a biomolecule in order to show efficacy. Among biomolecules, those containing an ʟ-Cys residue have the highest potential to be involved in reduction. Tautornerisation from HSCH2CH(NH3+)CO2¯ to the unusual zwitterion form ¯SCH2CH(NH3+)CO2H is the prerequisite for ʟ-Cys to become a potent reductant at a low pH