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PDBsum entry 1k9v
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Structural evidence for ammonia tunneling across the (beta alpha)(8) barrel of the imidazole glycerol phosphate synthase bienzyme complex.
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Authors
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A.Douangamath,
M.Walker,
S.Beismann-Driemeyer,
M.C.Vega-Fernandez,
R.Sterner,
M.Wilmanns.
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Ref.
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Structure, 2002,
10,
185-193.
[DOI no: ]
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PubMed id
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Abstract
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Since reactive ammonia is not available under physiological conditions,
glutamine is used as a source for the incorporation of nitrogen in a number of
metabolic pathway intermediates. The heterodimeric ImGP synthase that links
histidine and purine biosynthesis belongs to the family of glutamine
amidotransferases in which the glutaminase activity is coupled with a subsequent
synthase activity specific for each member of the enzyme family. Its X-ray
structure from the hyperthermophile Thermotoga maritima shows that the
glutaminase subunit is associated with the N-terminal face of the (beta
alpha)(8) barrel cyclase subunit. The complex reveals a putative tunnel for the
transfer of ammonia over a distance of 25 A. Although ammonia tunneling has been
reported for glutamine amidotransferases, the ImGP synthase has evolved a novel
mechanism, which extends the known functional properties of the versatile (beta
alpha)(8) barrel fold.
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Figure 1.
Figure 1. Reactions Catalyzed by the Glutaminase Subunit
HisH and the Cyclase Subunit HisF, which Constitute the ImGP
SynthaseThe products ImGP and AICAR are further used in
histidine and de novo purine biosynthesis, respectively.
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The above figure is
reprinted
by permission from Cell Press:
Structure
(2002,
10,
185-193)
copyright 2002.
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