Structural highlights
Publication Abstract from PubMedDyP-type peroxidases (DyP = dye decolorizing peroxidases) belong to the large group of heme peroxidases. They utilize hydrogen peroxide to catalyze oxidations of various organic compounds. AauDyPI from Auricularia auricula-judae (Fungi) was crystallized and its crystal structure was determined at 2.1 A resolution. The mostly helical structure also shows a beta-sheet motif typical for DyPs and Cld-related structures and includes the complete poypeptide chain. At the distal side of the heme molecule, a flexible aspartate residue (Asp168) plays a key role in catalysis. It guides incoming hydrogen peroxide toward the heme iron and mediates proton rearrangement in the process of Compound I formation. Afterwards, its side chain changes its conformation now pointing toward the protein backbone. We propose an extended functionality of Asp168, that acts like a gatekeeper by altering the width of the heme cavity access channel. Chemical modifications of potentially redox-active amino acids show that a tyrosine is involved in substrate interaction. Using spin trapping experiments a transient radical on the surface-exposed Tyr337 was identified as the oxidation site for bulky substrates. A possible long-range electron transfer (LRET) pathway from the surface of the enzyme to the redox cofactor (heme) is discussed. First Crystal Structure of a Fungal High-Redox Potential Dye-decolorizing Peroxidase: Substrate Interaction Sites and Long-Range Electron Transfer.,Strittmatter E, Liers C, Ullrich R, Wachter S, Hofrichter M, Plattner DA, Piontek K J Biol Chem. 2012 Dec 12. PMID:23235158[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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