5cib

Complex of yeast cytochrome c peroxidase (W191G) bound to 2,4-dimethylaniline with iso-1 cytochrome c

spinqualitylabelsall models 5cib, resolution 3.01Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5cib is a 4 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: 51S, HEM Related: 5cic, 5cid, 5cie, 5cif, 5cig, 5cih Activity: Cytochrome-c peroxidase, with EC number 1.11.1.5 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. [CYC1_YEAST] Electron carrier protein. The oxidized form of the cytochrome c heme group can accept an electron from the heme group of the cytochrome c1 subunit of cytochrome reductase. Cytochrome c then transfers this electron to the cytochrome oxidase complex, the final protein carrier in the mitochondrial electron-transport chain. Publication Abstract from PubMed The tryptophan 191 cation radical of cytochrome c peroxidase (CcP) compound I (Cpd I) mediates long-range electron transfer (ET) to cytochrome c (Cc). Here we test the effects of chemical substitution at position 191. CcP W191Y forms a stable tyrosyl radical upon reaction with peroxide and produces spectral properties similar to those of Cpd I but has low reactivity toward reduced Cc. CcP W191G and W191F variants also have low activity, as do redox ligands that bind within the W191G cavity. Crystal structures of complexes between Cc and CcP W191X (X = Y, F, or G), as well as W191G with four bound ligands reveal similar 1:1 association modes and heme pocket conformations. The ligands display structural disorder in the pocket and do not hydrogen bond to Asp235, as does Trp191. Well-ordered Tyr191 directs its hydroxyl group toward the porphyrin ring, with no basic residue in the range of interaction. CcP W191X (X = Y, F, or G) variants substituted with zinc-porphyrin (ZnP) undergo photoinduced ET with Cc(III). Their slow charge recombination kinetics that result from loss of the radical center allow resolution of difference spectra for the charge-separated state [ZnP(+), Cc(II)]. The change from a phenyl moiety at position 191 in W191F to a water-filled cavity in W191G produces effects on ET rates much weaker than the effects of the change from Trp to Phe. Low net reactivity of W191Y toward Cc(II) derives either from the inability of ZnP(+) or the Fe-CcP ferryl to oxidize Tyr or from the low potential of the resulting neutral Tyr radical. Constraints on the Radical Cation Center of Cytochrome c Peroxidase for Electron Transfer from Cytochrome c.,Payne TM, Yee EF, Dzikovski B, Crane BR Biochemistry. 2016 Aug 30;55(34):4807-22. doi: 10.1021/acs.biochem.6b00262. Epub , 2016 Aug 17. PMID:27499202 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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