5ccp

HISTIDINE 52 IS A CRITICAL RESIDUE FOR RAPID FORMATION OF CYTOCHROME C PEROXIDASE COMPOUND I

spinqualitylabelsall models 5ccp, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5ccp is a 1 chain structure with sequence from Atcc 18824. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: HEM Related: 1ccp, 2ccp, 3ccp, 4ccp, 6ccp, 7ccp, 1cpd, 1cpe, 1cpf, 1cpg, 1bej, 1bem, 1beq, 1bes 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. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The crystal structure and reactivity with hydrogen peroxide are reported for a mutant of a cloned cytochrome c peroxidase [CcP(MI)], in which the conserved distal His (His-52) is replaced with Leu. The reaction of the H52L enzyme with peroxide was examined as a function of pH in 0.1 M phosphate buffers and buffers in which nitrate was used to adjust the ionic strength. The pH-independent bimolecular rate constant for the reaction of H52L with peroxide was 731 +/- 44 and 236 +/- 14 M-1 s-1 in phosphate and nitrate-containing buffers, respectively. This represents a 10(5)-fold decrease in rate relative to the CcP(MI) parent under comparable conditions. Single-crystal diffraction studies showed that no dramatic changes in the structure or in the accessibility of the heme binding site were caused by the mutation. Rather, the mutation caused significant structural changes only at residue 52 and the nearby active-site water molecules. The residual reactivity of the H52L enzyme with peroxide was pH- and buffer-dependent. In nitrate-containing buffer, the apparent bimolecular rate constant for the reaction with peroxide decreased with decreasing pH; the loss of reactivity correlated with protonation of a group with an apparent pKA = 4.5. Protonation of the group caused a loss of reactivity with peroxide. This is in contrast to the CcP(MI) parent enzyme, as well as all other mutants that have been examined, where the loss of reactivity correlates with protonation of an enzyme group with an apparent pKA = 5.4.(ABSTRACT TRUNCATED AT 250 WORDS) Histidine 52 is a critical residue for rapid formation of cytochrome c peroxidase compound I.,Erman JE, Vitello LB, Miller MA, Shaw A, Brown KA, Kraut J Biochemistry. 1993 Sep 21;32(37):9798-806. PMID:8396972 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Cytochrome c peroxidase 3D structures

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