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Abstract

Peroxidases are enzymes responsible for scavenging H₂O₂ in every lifeform. Since they often show high level of homology, it was believed that the process have the same chemical origins. However the latest studies show that the transferability of the reaction mechanism is not reliable, therefore more intensive studies on the peroxidases family has to be done. Especially heme peroxidases show a large diversity in respect to conformation of aminoacids in the active site, as well as the nature of the intermediate species during the hydrogen peroxide scavenging process.
Ascorbate peroxidase is of particular interest since it is the main enzyme responsible for the process in plants and algae. While the first intermediate of the process (Compound I) is well known, the latter active species (Compound II) has still unknown nature. The recent studies show discrepancies, especially in the nature of the apical heme ligand: while crystallographic data correspond to an hydroxo species, the spectroscopic measurements show oxo origin. In current work we tried to answer the open question with use of computational methods. We performed MD equlibration of the initial structure and use it further with partitioning the system into QM and MM part within QM/MM approach.
With so obtained models we performed analysis of electronic structure and calculated Mössbauer parameters.