1ecb: Difference between revisions
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==Overview== | ==Overview== | ||
Activation of gluatmine phosphoribosylpyrophosphate (RPPP) | Activation of gluatmine phosphoribosylpyrophosphate (RPPP) amidotransferase (GPATase) by binding of a PRPP substrate analog results in the formation of a 20 A channel connecting the active site for glutamine hydrolysis in one domain with the PRPP site in a second domain. This solvent-inaccessible channel permits transfer of the NH3 intermediate between the two active sites. Tunneling of NH3 may be a common mechanism for glutamine amidotransferase-catalyzed nitrogen transfer and for coordination of catalysis at two distinct active sites in complex enzymes. The 2.4 A crystal structure of the active conformer of GPATase also provides the first description of an intact active site for the phosphoribosyltransferase (PRTase) family of nucleotide synthesis and salvage enzymes. Chemical assistance to catalysis is provided primarily by the substrate and secondarily by the enzyme in the proposed structure-based mechanism. Different catalytic and inhibitory modes of divalent cation binding to the PRTase active site are revealed in the active conformer of the enzyme and in a feedback-inhibited GMP complex. | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Krahn, J | [[Category: Krahn, J M.]] | ||
[[Category: Smith, J | [[Category: Smith, J L.]] | ||
[[Category: 5GP]] | [[Category: 5GP]] | ||
[[Category: MG]] | [[Category: MG]] | ||
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[[Category: transferase]] | [[Category: transferase]] | ||
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Revision as of 13:26, 21 February 2008
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ESCHERICHIA COLI GLUTAMINE PHOSPHORIBOSYLPYROPHOSPHATE (PRPP) AMIDOTRANSFERASE COMPLEXED WITH 2 GMP, 1 MG PER SUBUNIT
OverviewOverview
Activation of gluatmine phosphoribosylpyrophosphate (RPPP) amidotransferase (GPATase) by binding of a PRPP substrate analog results in the formation of a 20 A channel connecting the active site for glutamine hydrolysis in one domain with the PRPP site in a second domain. This solvent-inaccessible channel permits transfer of the NH3 intermediate between the two active sites. Tunneling of NH3 may be a common mechanism for glutamine amidotransferase-catalyzed nitrogen transfer and for coordination of catalysis at two distinct active sites in complex enzymes. The 2.4 A crystal structure of the active conformer of GPATase also provides the first description of an intact active site for the phosphoribosyltransferase (PRTase) family of nucleotide synthesis and salvage enzymes. Chemical assistance to catalysis is provided primarily by the substrate and secondarily by the enzyme in the proposed structure-based mechanism. Different catalytic and inhibitory modes of divalent cation binding to the PRTase active site are revealed in the active conformer of the enzyme and in a feedback-inhibited GMP complex.
About this StructureAbout this Structure
1ECB is a Single protein structure of sequence from Escherichia coli with and as ligands. Active as Amidophosphoribosyltransferase, with EC number 2.4.2.14 Known structural/functional Sites: , , , , , , and . Full crystallographic information is available from OCA.
ReferenceReference
Coupled formation of an amidotransferase interdomain ammonia channel and a phosphoribosyltransferase active site., Krahn JM, Kim JH, Burns MR, Parry RJ, Zalkin H, Smith JL, Biochemistry. 1997 Sep 16;36(37):11061-8. PMID:9333323
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