Enzyme-substrate complex extradiol cleaving

Table 3 compares some key properties of the enzyme-substrate complexes of the intradiol and extradiol cleaving dioxygenases. A mechanism for extradiol cleavage must account for the differing metal requirements of the two classes of enzymes and their distinct regiospecificities. A key difference is the reactivity of the ES complexes toward NO. Whereas the ES complexes of extradiol enzymes readily react with NO to form ES—NO adducts, those of intradiol enzymes do not react with NO unless the Fe(III) center is reduced prior to exposure to NO [167], Thus the Fe(II) center in the extradiol cleaving enzymes appears... 

---