Molecular mechanism of action of the radioprotective substance WR 2721

The radioprotective effect of WR 2721 on catalase and the type and loci of its interaction with the enzyme have been investigated by means of spectrophotometric and electron spin resonance, (ESR) methods. The radiation damage, indicated by a change in enzymatic activity and in the Soret absorption band, has been the less the larger the WR 2721 concentration. In the case of ESR investigations, addition of WR 2721 has resulted in a reduction of the spin concentration of Cu-2+. Since cysteamine has exhibited similar results, however, to a lesser extent, it can be assumed that the RS-ions are responsible for the protective effect. From the results obtained it can be concluded that (the dephosphorilized) WR 2721 forms a complex with the enzyme and acts as an electron donor.