1m85
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Structure of Proteus mirabilis catalase for the native form
OverviewOverview
A catalase from a peroxide resistant mutant of Proteus mirabilis binds, NADPH tightly. Interestingly, this enzyme can be stripped of NADPH without, loss of the catalatic activity. It is the only known non-mammalian, catalase able to bind NADPH. The structure without cofactor was solved by, molecular replacement using the structure of beef liver catalase as a, model. The structure was refined to an R-factor of 19.3% in the range 8 to, 2.2 A resolution. According to the sequence, a methionine sulphone was, positioned in the haem active site. This oxidized form of methionine is, particular to Proteus mirabilis catalase and likely to produce some steric, hindrance in the active site. Two important water molecules are positioned, in the haem distal site. These two water molecules are not located in the, structure of beef liver catalase, but are supposed to account for the, catalytic mechanism. The liganded form was obtained by soaking crystals of, the unliganded form into an NADPH solution. The structure was refined to, an R-factor of 15.9% in the range of 8 to 3.1 A resolution using the, unliganded structure as a model. The NADPH was clearly located in the, electron density map with the same conformation as in beef liver catalase., The NADPH binding induces slight structural changes. However, the, imidazole ring of a histidine residue (His284) rotates about 50 degrees to, accommodate the cofactor. The electron transfer from NADPH to the haem, molecule was examined and several pathways are proposed.
About this StructureAbout this Structure
1M85 is a [Protein single] structure of sequence from [Proteus mirabilis] with SO4, HEM and GOL as [ligands]. This structure superseeds the now removed PDB entries 2CAE and 1CAE.
ReferenceReference
Crystal structure of Proteus mirabilis PR catalase with and without bound NADPH., Gouet P, Jouve HM, Dideberg O, J Mol Biol. 1995 Jun 23;249(5):933-54. PMID:7791219
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