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| {{STRUCTURE_1ofk| PDB=1ofk | SCENE= }} | | {{STRUCTURE_1ofk| PDB=1ofk | SCENE= }} |
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| '''RECOMBINANT SPERM WHALE MYOGLOBIN F43H, H64L MUTANT (MET)'''
| | ===RECOMBINANT SPERM WHALE MYOGLOBIN F43H, H64L MUTANT (MET)=== |
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| ==Overview==
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| To clarify how the location of distal histidine affects the activation process of H2O2 by heme proteins, we have characterized reactions with H2O2 for the L29H/H64L and F43H/H64L mutants of sperm whale myoglobin (Mb), designed to locate the histidine farther from the heme iron. Whereas the L29H/H64L double substitution retarded the reaction with H2O2, an 11-fold rate increase versus wild-type Mb was observed for the F43H/H64L mutant. The Vmax values for 1-electron oxidations by the myoglobins correlate well with the varied reactivities with H2O2. The functions of the distal histidine as a general acid-base catalyst were examined based on the reactions with cumene hydroperoxide and cyanide, and only the histidine in F43H/H64L Mb was suggested to facilitate heterolysis of the peroxide bond. The x-ray crystal structures of the mutants confirmed that the distal histidines in F43H/H64L Mb and peroxidase are similar in distance from the heme iron, whereas the distal histidine in L29H/H64L Mb is located too far to enhance heterolysis. Our results indicate that the proper positioning of the distal histidine is essential for the activation of H2O2 by heme enzymes.
| | The line below this paragraph, {{ABSTRACT_PUBMED_9915818}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 9915818 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_9915818}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Oxygen transport]] | | [[Category: Oxygen transport]] |
| [[Category: Peroxidase activity]] | | [[Category: Peroxidase activity]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 03:47:04 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 23:06:52 2008'' |
