2x08

cytochrome c peroxidase: ascorbate bound to the engineered ascorbate binding sitecytochrome c peroxidase: ascorbate bound to the engineered ascorbate binding site

Structural highlights 2x08 is a 1 chain structure with sequence from Saccharomyces cerevisiae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.01Å Ligands: , Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CCPR_YEAST Destroys radicals which are normally produced within the cells and which are toxic to biological systems. Publication Abstract from PubMed The binding of substrates to heme enzymes has been widely assumed to occur at the so-called delta-heme edge. Recently, however, a number of examples have appeared in which substrate binding at an alternative site, the gamma-heme edge, is also possible. In previous work [Sharp et al. (2003) Nat. Struct. Biol. 10, 303-307], we showed that binding of ascorbate to ascorbate peroxidase occurred at the gamma-heme edge. Here, we show that the closely related cytochrome c peroxidase enzyme can duplicate the substrate binding properties of ascorbate peroxidase through the introduction of relatively modest structural changes at Tyr36 and Asn184. Hence, crystallographic data for the Y36A/N184R/W191F triple variant of cytochrome c peroxidase shows ascorbate bound to the gamma-heme edge, with hydrogen bonds to the heme propionate and Arg184. In parallel mechanistic studies in variants incorporating the W191F mutation, we show that a transient porphyrin pi-cation radical in Compound I of cytochrome c peroxidase, analogous to that observed in ascorbate peroxidase, is competent for ascorbate oxidation but that under steady state conditions this intermediate decays too rapidly to sustain efficient turnover of ascorbate. The results are discussed in terms of our more general understanding of substrate oxidation across other heme proteins, and the emerging role of the heme propionates at the gamma-heme edge. Engineering the substrate specificity and reactivity of a heme protein: creation of an ascorbate binding site in cytochrome c peroxidase.,Murphy EJ, Metcalfe CL, Basran J, Moody PC, Raven EL Biochemistry. 2008 Dec 30;47(52):13933-41. PMID:19061385 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Cytochrome c peroxidase 3D structures

spinqualitylabelsall models 2x08, resolution 2.01Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image