1.13.11.3	3,4-dihydroxybenzoate + O2 = 3-carboxy-cis,cis-muconate	proposed reaction mechanism	
1.13.11.3	3,4-dihydroxybenzoate + O2 = 3-carboxy-cis,cis-muconate	proposed mechanism based on Mössbauer, EPR and inhibition kinetic data	
1.13.11.3	3,4-dihydroxybenzoate + O2 = 3-carboxy-cis,cis-muconate	examining a distorted trigonal-bipyramidal geometry observed for the non-heme iron center in protocatechuate 3,4-dioxygenase by utilizing a sterically hindered iron salen complex gives following results: the extent of a structural change of the iron center from a preferred square-pyramidal to a distorted trigonal-bipyramidal geometry varies with the external ligand that is bound in the order Cl <<EtO <H2O. The distortion in the model system is not due to steric repulsions but electronic interactions between the external ligand and the iron center. The distorted trigonal-bipyramidal iron site might not be preorganized by a 3,4-PCD protein but could be electronically induced upon the binding of an external hydrocide ligand to the iron(3)center. The distorted trigonal-bipyramidal distortion geometry in 3,4-PCD may serve to open the binding site for the catechol substrate.	
1.13.11.3	3,4-dihydroxybenzoate + O2 = 3-carboxy-cis,cis-muconate	the computational (hybrid density functional method B3LYP) results of the catalytic cycle of the intradiol dioxygenases suggest: (1)binging of the substrate as a dianion (2) binding of dioxygen to the metal aided by an electron transfer from the substrate to O2 (3) formation of a bridging peroxo intermediate and its conformational change, which opens the coordination site trans to His462, (4) binding of a neutral XOH ligand (H2O or Tyr447) at the open site, (5) proton transfer from XOH to the neighboring peroxo ligand yielding the hydroperoxo intermediate, (6) a Criegee rearrangment leading to the anhydride intermediate (the criegee mechanism requires an in-plane oriantation of the involved two oxygen and two carbon atoms. Under some conditions homolytic O-O bond cleavage might compete with the Criegee rearangment.) and (7) hydrolysis of the anhydride to the final acyclic product.