The catalysis of class III plant peroxidases is described based on the reaction scheme of horseradish peroxidase. The mechanism consists in four distinct steps: (a) binding of peroxide to the heme-FeIII to form a very unstable peroxide complex, Compound 0; (b) oxidation of the iron to generate Compound I, a ferryl species with a π-cation radical in the porphyrin ring; (c) reduction of Compound I by one substrate molecule to produce a substrate radical and another ferryl species, Compound II; (d) reduction of Compound II by a second substrate molecule to release a second substrate radical and regenerate the native enzyme. Under unfavourable conditions some inactive enzyme species can be formed, known as dead-end species. Two calcium ions are normally found in plant peroxidases and appear to be important for the catalytic efficiency.
Longu, S., Medda, R., Padiglia, A., Pedersen, J.z., Floris, G. (2004). The reaction mechanism of plant peroxidases. ITALIAN JOURNAL OF BIOCHEMISTRY, 53, 42-46.
The reaction mechanism of plant peroxidases.
PEDERSEN, JENS ZACHO;
2004-01-01
Abstract
The catalysis of class III plant peroxidases is described based on the reaction scheme of horseradish peroxidase. The mechanism consists in four distinct steps: (a) binding of peroxide to the heme-FeIII to form a very unstable peroxide complex, Compound 0; (b) oxidation of the iron to generate Compound I, a ferryl species with a π-cation radical in the porphyrin ring; (c) reduction of Compound I by one substrate molecule to produce a substrate radical and another ferryl species, Compound II; (d) reduction of Compound II by a second substrate molecule to release a second substrate radical and regenerate the native enzyme. Under unfavourable conditions some inactive enzyme species can be formed, known as dead-end species. Two calcium ions are normally found in plant peroxidases and appear to be important for the catalytic efficiency.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.