1hp1

From Proteopedia

Revision as of 10:06, 23 March 2008

5'-NUCLEOTIDASE (OPEN FORM) COMPLEX WITH ATP

Overview

5'-Nucleotidase belongs to a large superfamily of distantly related dinuclear metallophosphatases including the Ser/Thr protein phosphatases and purple acid phosphatases. The protein undergoes a 96 degrees domain rotation between an open (inactive) and a closed (active) enzyme form. Complex structures of the closed form with the products adenosine and phosphate, and with the substrate analogue inhibitor alpha,beta-methylene ADP, have been determined at 2.1 A and 1.85 A resolution, respectively. In addition, a complex of the open form of 5'-nucleotidase with ATP was analyzed at a resolution of 1.7 A. These structures show that the adenosine group binds to a specific binding pocket of the C-terminal domain. The adenine ring is stacked between Phe429 and Phe498. The N-terminal domain provides the ligands to the dimetal cluster and the conserved His117, which together form the catalytic core structure. However, the three C-terminal arginine residues 375, 379 and 410, which are involved in substrate binding, may also play a role in transition-state stabilization. The beta-phosphate group of the inhibitor is terminally coordinated to the site 2 metal ion. The site 1 metal ion coordinates a water molecule which is in an ideal position for a nucleophilic attack on the phosphorus atom, assuming an in-line mechanism of phosphoryl transfer. Another water molecule bridges the two metal ions.

About this Structure

1HP1 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Mechanism of hydrolysis of phosphate esters by the dimetal center of 5'-nucleotidase based on crystal structures., Knofel T, Strater N, J Mol Biol. 2001 May 25;309(1):239-54. PMID:11491293

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