Pyrocatechol dioxygenases

Pyrocatechol dioxygenases. 6, 325 Pyrocatechol violet metallochromic indicator, 1,556 Pyrogallol... 

Dioxygenases catalyze the incorporation of both atoms of molecular oxygen into the substrate. Microbial pyrocatechol dioxygenases contain non-heme iron as the sole cofactor and catalyze the oxidative cleavage of pyrocatechol to as,cis-muconic acid (intradiol equation 19) or to a-hydroxymuconic s-semialdehyde (extradiol equation 20).63"65 On... 

Both of these systems activate O2 via a two-equivalent reduction (without the protein catalysts this would give HOOH). In contrast, pyrocatechol dioxygenase (PDO) (a nonheme iron protein) activates 2 without a reductive cofactor (equation 106). 

Pyrocatechol dioxygenases, 325 Pyromctallurgy, 780, 832-835 Pyrophosphatase inorganic activation, 581 Pyrophosphates... 

Tsuji and coworkers reported that copper(I) chloride in the presence of pyridine, methanol and dioxygen promotes the stoichiometric oxidation of pyrocatechol to methyl muconate.606 Labeling lg02 studies have shown that only one atom of the dioxygen molecule is incorporated in the substrate, while the other one is transformed into water as in enzymic monooxygenases (equation 275)607 (and not as in dioxygenases, viz. pyrocatechase). This reaction has been shown by Rogic et al. to proceed via two steps (equation 276).580,58 ... 

Pyrocatechase (PC) is representative of a class of proteins that facilitates the transfer of both atoms of O2 to a substrate molecule. With this particular dioxygenase, pyrocatechol is transformed to mnconic acid (eqnation 29). 

---