1ecb: Difference between revisions
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==Overview== | ==Overview== | ||
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. .. | 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== | ||
1ECB is a | 1ECB is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with MG and 5GP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Amidophosphoribosyltransferase Amidophosphoribosyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.2.14 2.4.2.14] Structure known Active Sites: NTA, NTB, NTC, NTD, PRA, PRB, PRC and PRT. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1ECB OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: transferase]] | [[Category: transferase]] | ||
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 12:40:59 2007'' | ||
