1gph
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(New page: 200px<br /><applet load="1gph" size="450" color="white" frame="true" align="right" spinBox="true" caption="1gph, resolution 3.0Å" /> '''STRUCTURE OF THE ALLO...)
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STRUCTURE OF THE ALLOSTERIC REGULATORY ENZYME OF PURINE BIOSYNTHESIS
Overview
Multi-wavelength anomalous diffraction (MAD) has been used to determine, the structure of the regulatory enzyme of de novo synthesis of purine, nucleotides, glutamine 5-phosphoribosyl-1-pyrophosphate (PRPP), amidotransferase, from Bacillus subtilis. This allosteric enzyme, a, 200-kilodalton tetramer, is subject to end product regulation by purine, nucleotides. The metalloenzyme from B. subtilis is a paradigm for the, higher eukaryotic enzymes, which have been refractory to isolation in, stable form. The two folding domains of the polypeptide are correlated, with functional domains for glutamine binding and for transfer of ammonia, to the substrate PRPP. Eight molecules of the feedback inhibitor adenosine, monophosphate (AMP) are bound to the tetrameric enzyme in two types of, binding sites: the PRPP catalytic site of each subunit and an unusual, regulatory site that is immediately adjacent to each active site but is, between subunits. An oxygen-sensitive [4Fe-4S] cluster in each subunit is, proposed to regulate protein turnover in vivo and is distant from the, catalytic site. Oxygen sensitivity of the cluster is diminished by AMP, which blocks a channel through the protein to the cluster. The structure, is representative of both glutamine amidotransferases and, phosphoribosyltransferases.
About this Structure
1GPH is a Single protein structure of sequence from Bacillus subtilis with SF4 and AMP as ligands. Active as Amidophosphoribosyltransferase, with EC number 2.4.2.14 Full crystallographic information is available from OCA.
Reference
Structure of the allosteric regulatory enzyme of purine biosynthesis., Smith JL, Zaluzec EJ, Wery JP, Niu L, Switzer RL, Zalkin H, Satow Y, Science. 1994 Jun 3;264(5164):1427-33. PMID:8197456
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