1dnp: Difference between revisions

[[Image:1dnp.jpg|left|200px]]<br /><applet load="1dnp" size="350" color="white" frame="true" align="right" spinBox="true"  

Photolyase repairs ultraviolet (UV) damage to DNA by splitting the cyclobutane ring of the major UV photoproduct, the cis, syn-cyclobutane pyrimidine dimer (Pyr &lt;&gt; Pyr). The reaction is initiated by blue light and proceeds through long-range energy transfer, single electron transfer, and enzyme catalysis by a radical mechanism. The three-dimensional crystallographic structure of DNA photolyase from Escherichia coli is presented and the atomic model was refined to an R value of 0.172 at 2.3 A resolution. The polypeptide chain of 471 amino acids is folded into an amino-terminal alpha/beta domain resembling dinucleotide binding domains and a carboxyl-terminal helical domain; a loop of 72 residues connects the domains. The light-harvesting cofactor 5,10-methenyltetrahydrofolylpolyglutamate (MTHF) binds in a cleft between the two domains. Energy transfer from MTHF to the catalytic cofactor flavin adenine dinucleotide (FAD) occurs over a distance of 16.8 A. The FAD adopts a U-shaped conformation between two helix clusters in the center of the helical domain and is accessible through a hole in the surface of this domain. Dimensions and polarity of the hole match those of a Pyr &lt;&gt; Pyr dinucleotide, suggesting that the Pyr &lt;&gt; Pyr "flips out" of the helix to fit into this hole, and that electron transfer between the flavin and the Pyr &lt;&gt; Pyr occurs over van der Waals contact distance.

1DNP 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 <scene name='pdbligand=FAD:'>FAD</scene> and <scene name='pdbligand=MHF:'>MHF</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Deoxyribodipyrimidine_photo-lyase Deoxyribodipyrimidine photo-lyase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.1.99.3 4.1.99.3] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DNP OCA].  

[[Category: Park, H W.]]

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