Haem peptide/protein interaction. Part 6: The kinetic mechanisms of the interactions with, and inhibition of enzymic activity of the human erythrocyte glutathione S-transferase isoenzyme rho (p), by haem octa-, nona-, and undecapeptides MP-8/-9/-11.

The binding of the cytochrome-c derived haem peptides microperoxidase-8, -9, and -11 (MP-8, -9, and -11) to the human erythrocyte glutathione S-transferase rho (GST-p) enzyme is demonstrated. Inhibition by the haem peptides of the enzymic conjugation of glutathione (GSH) with the electrophilic cosubstrate 1-chloro-2, 4-dinitrobenzene (CDNB) is mixed-type with respect to CDNB, and Ki, the inhibition constant, increases with increasing length of the peptide chain. The results obtained here for the GST-p are compared to those published recently for the previously-supposed identical isoenzyme human placental GST-pi.