EC Number   |
Reaction |
Reference |
|---|
    1.14.13.2 | 4-hydroxybenzoate + NADPH + H+ + O2 = 3,4-dihydroxybenzoate + NADP+ + H2O |
bi uni uni uni ping-pong mechanism |
390023 |
| 1.14.13.2 | 4-hydroxybenzoate + NADPH + H+ + O2 = 3,4-dihydroxybenzoate + NADP+ + H2O |
catalytic cycle of enzyme PHBH, overview |
-, 764168 |
| 1.14.13.2 | 4-hydroxybenzoate + NADPH + H+ + O2 = 3,4-dihydroxybenzoate + NADP+ + H2O |
kinetic scheme of reductive half-reaction, flavin movement can occur in the presence or absence of NADPH, but NADPH stimulates movement to the reactive conformation required for hydride transfer |
661173 |
| 1.14.13.2 | 4-hydroxybenzoate + NADPH + H+ + O2 = 3,4-dihydroxybenzoate + NADP+ + H2O |
rate of formation of the flavin hydroperoxide is not influenced by pH-change. Rate of hydroxylation reaction increases with pH. The H-bond network abstracts the phenolic proton from p-hydroxybenzoate in the transition state of oxygen transfer. Product deprotonation enhances the rate of a specific conformational change required for both product relase and the elimination of water |
658045 |
| 1.14.13.2 | 4-hydroxybenzoate + NADPH + H+ + O2 = 3,4-dihydroxybenzoate + NADP+ + H2O |
the catalytic mechanism of PHBH from Pseudomonas species includes the reductive half-reaction, in which 4-hydroxybenzoate (4-HB) and some substrate analogues can act as effectors by stimulating the two-electron reduction of the FAD cofactor by NAD(P)H. In the oxidative half-reaction, the enzyme activates molecular oxygen through formation of a transiently stable flavin C4a-hydroperoxide and subsequently regioselectively incorporates one oxygen atom into the substrate. Based on the structural and kinetic properties of wild-type enzyme and a range of protein variants, the catalytic cycle of PHBH has been proposed to involve flavin movements in and out of the active site and opening and closure of a substrate transport channel. The C3 atom of the aromatic ring of the substrate is in close vicinity of the C4a atom of the isoalloxazine ring of FAD, which occupies the conformation. This active site configuration allows the attack of the flavin C4a-hydroperoxide oxygenation species onto the C3 atom of the substrate. The electrophilic ortho-hydroxylation reaction is stimulated by deprotonation of the phenolic moiety of 4-hydroxybenzoate, as facilitated by a water involved proton relay network that connects Tyr201 via Tyr385 and His72 with the protein surface |
-, 764036 |
