1z84
From Proteopedia
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'''X-ray structure of galt-like protein from arabidopsis thaliana at5g18200''' | '''X-ray structure of galt-like protein from arabidopsis thaliana at5g18200''' | ||
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[[Category: Jr., G N.Phillips.]] | [[Category: Jr., G N.Phillips.]] | ||
[[Category: Mccoy, J G.]] | [[Category: Mccoy, J G.]] | ||
| - | [[Category: | + | [[Category: Amp]] |
| - | [[Category: | + | [[Category: Center for eukaryotic structural genomic]] |
| - | [[Category: | + | [[Category: Cesg]] |
| - | [[Category: | + | [[Category: Galt]] |
| - | [[Category: | + | [[Category: Protein structure initiative]] |
| - | [[Category: | + | [[Category: Psi]] |
| - | [[Category: | + | [[Category: Structural genomic]] |
| - | [[Category: | + | [[Category: Zinc]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 17:17:45 2008'' | |
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Revision as of 14:17, 3 May 2008
X-ray structure of galt-like protein from arabidopsis thaliana at5g18200
Overview
The X-ray crystal structure of the At5g18200.1 protein has been determined to a nominal resolution of 2.30 A. The structure has a histidine triad (HIT)-like fold containing two distinct HIT-like motifs. The sequence of At5g18200.1 indicates a distant family relationship to the Escherichia coli galactose-1-P uridylyltransferase (GalT): the determined structure of the At5g18200.1 protein confirms this relationship. The At5g18200.1 protein does not demonstrate GalT activity but instead catalyzes adenylyl transfer in the reaction of ADP-glucose with various phosphates. The best acceptor among those evaluated is phosphate itself; thus, the At5g18200.1 enzyme appears to be an ADP-glucose phosphorylase. The enzyme catalyzes the exchange of (14)C between ADP-[(14)C]glucose and glucose-1-P in the absence of phosphate. The steady state kinetics of exchange follows the ping-pong bi-bi kinetic mechanism, with a k(cat) of 4.1 s(-)(1) and K(m) values of 1.4 and 83 microM for ADP-[(14)C]glucose and glucose-1-P, respectively, at pH 8.5 and 25 degrees C. The overall reaction of ADP-glucose with phosphate to produce ADP and glucose-1-P follows ping-pong bi-bi steady state kinetics, with a k(cat) of 2.7 s(-)(1) and K(m) values of 6.9 and 90 microM for ADP-glucose and phosphate, respectively, at pH 8.5 and 25 degrees C. The kinetics are consistent with a double-displacement mechanism that involves a covalent adenylyl-enzyme intermediate. The X-ray crystal structure of this intermediate was determined to 1.83 A resolution and shows the AMP group bonded to His(186). The value of K(eq) in the direction of ADP and glucose-1-P formation is 5.0 at pH 7.0 and 25 degrees C in the absence of a divalent metal ion, and it is 40 in the presence of 1 mM MgCl(2).
About this Structure
1Z84 is a Single protein structure of sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA.
Reference
Structure and mechanism of an ADP-glucose phosphorylase from Arabidopsis thaliana., McCoy JG, Arabshahi A, Bitto E, Bingman CA, Ruzicka FJ, Frey PA, Phillips GN Jr, Biochemistry. 2006 Mar 14;45(10):3154-62. PMID:16519510 Page seeded by OCA on Sat May 3 17:17:45 2008
