Interaction of the Hemin 2 and 4 Substituents with Apo Horseradish Peroxidase

2-Formyl-4-vinyl-deuterohemin- and 2-vinyl-4-formyl-deuterohemin-substituted horseradish peroxidase were prepared from apoperoxidase and the respective hemins. The 2 hemins bind at different rates to the apoprotein and the resultant substituted peroxidases possess different visible spectra and activities. Thus, the hemin 2 and 4 substituents interact with apoperoxidase and are not exposed to the solvent.