Fluphenazine photoaffinity labelling of binding sites for phenothiazine inhibitors of trypanothione reductase

Photolysis of fluphenazine, a competitive inhibitor of trypanothione reductase in the presence of trypanothione reductase leads to irreversible, time-dependent inactivation, which is not dependent on the presence of molecular oxygen in the medium and can be protected against by the presence of trypanothione substrate; MALDI and electrospray mass spectrometric analyses shows that 2-5 equiv. of the phenothiazine are incorporated per enzyme subunit.