Two epitopes responsible for the catalytic activity of heme oxygenase-1 identified by phage display.

Heme oxygenase-1 (HO-1) catalyzes the oxidative degradation of heme. The catalytic mechanism of the HO-1 reaction has been determined gradually by studies of its crystal structure and HO-1 mutants. However, the neutralizing epitopes responsible for HO-1 activity remain elusive. Screening of a phage display library revealed four epitopes that could interact with the polyclonal antibody prepared by immunizing rabbits with the purified HO-1 protein. Two of these four epitopes are responsible for HO-1 catalytic activity because their antibodies were able to neutralize HO-1 activity. The results of the present study shed further light on the molecular character of HO-1.