2j2m

File:2j2m.jpg

spinqualitylabelsall models 2j2m, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CRYSTAL STRUCTURE ANALYSIS OF CATALASE FROM EXIGUOBACTERIUM OXIDOTOLERANS

OverviewOverview

A catalase that exhibits a high level of activity and a rapid reaction, with organic peroxides has been purified from Exiguobacterium, oxidotolerans T-2-2T (EKTA catalase). The amino acid sequence of EKTA, catalase revealed that it is a novel clade 1 catalase. Amino acid residues, in the active site around the protoheme are conserved in the primary, structure of EKTA catalase. Although the general interactions of molecules, larger than hydrogen peroxide with catalases are strongly inhibited, because of the selection role of long and narrow channels in the substrate, reaching the active site, the formation rate of reactive intermediates, (compound I) in the reaction of EKTA catalase with peracetic acid is 77, times higher than that of bovine liver catalase (BLC) and 1200 times, higher than that of Micrococcus luteus catalase (MLC). The crystal, structure of EKTA catalase has been determined and refined to 2.4 A, resolution. The main channel structure of EKTA catalase is different from, those of BLC and MLC. The rate constant of compound I formation in, catalases decreased with an increase in the molecular size of the, substrate. For EKTA catalase with a larger bottleneck 15 A from the iron, (entrance of narrow channel) in the main channel, a lower rate of, reduction in compound I formation rate with an increase in the molecular, size of substrates was found. The increase in the rate constant of, compound I formation in these catalases was directly proportional to the, increase in the size of the bottleneck in the main channel when molecules, of substrates larger than H2O2, such as organic peroxides, are used in the, reaction. The results indicate that the size of the bottleneck in the main, channel in catalase is an important factor in defining the rate of, compound I formation corresponding to the molecular size of the, substrates, and this was demonstrated. The Leu149-Ile180 and Asp109-Met167, combinations at the entrance of the narrow channel in EKTA catalase, determine the size of the bottleneck, and each atom-to-atom distance for, the combination of residues was larger than those of corresponding, combinations of amino acid residues in BLC and MLC. The combination of, these four amino acids is quite specific in EKTA catalase as compared with, the combinations in other catalases in the gene database (compared with, more than 432 catalase genes in the database).

About this StructureAbout this Structure

2J2M is a Single protein structure of sequence from Exiguobacterium oxidotolerans with HEM as ligand. Active as Catalase, with EC number 1.11.1.6 Known structural/functional Site: . Full crystallographic information is available from OCA.

ReferenceReference

Relationship between the size of the bottleneck 15 A from iron in the main channel and the reactivity of catalase corresponding to the molecular size of substrates., Hara I, Ichise N, Kojima K, Kondo H, Ohgiya S, Matsuyama H, Yumoto I, Biochemistry. 2007 Jan 9;46(1):11-22. PMID:17198371

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