 activ inactiv p-hydroxyphenylpyruv hydroxylas 1 p-hydroxyphenylpyruv hydroxylas ec 1 99 1 14 revers inactiv dialysi storag purif involv ammonium sulfat fraction treatment oxid agent inact enzym reactiv reduc agent 2 metal-chelat agent inhibit enzym activ 1 10- phenanthrolin 4 7-diphenyl-1 10-phenanthrolin fe sensit inhibit 2 9-dimethyl-1 10-phenanthrolin cu specif 1 10-phenanthrolin-treat p-hydroxyphenylpyruv hydroxyl- as reactiv fe presenc reduc agent indic role fe enzym activ 3 nonoxid sulfhydryl reagent materi inhibit enzym activ condit 