1ofk
From Proteopedia
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RECOMBINANT SPERM WHALE MYOGLOBIN F43H, H64L MUTANT (MET)
Overview
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.
About this Structure
1OFK is a Single protein structure of sequence from Physeter catodon with SO4 and HEM as ligands. Full crystallographic information is available from OCA.
Reference
Effects of the location of distal histidine in the reaction of myoglobin with hydrogen peroxide., Matsui T, Ozaki S, Liong E, Phillips GN Jr, Watanabe Y, J Biol Chem. 1999 Jan 29;274(5):2838-44. PMID:9915818
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