1pdh: Difference between revisions

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

The flavin prosthetic group (FAD) of p-hydroxybenzoate hydroxylase from Pseudomonas fluorescens was replaced by a stereochemical analog, which is spontaneously formed from natural FAD in alcohol oxidases from methylotrophic yeasts. Reconstitution of p-hydroxybenzoate hydroxylase from apoprotein and modified FAD is a rapid process complete within seconds. Crystals of the enzyme-substrate complex of modified FAD-containing p-hydroxybenzoate hydroxylase diffract to 2.1 A resolution. The crystal structure provides direct evidence for the presence of an arabityl sugar chain in the modified form of FAD. The isoalloxazine ring of the arabinoflavin adenine dinucleotide (a-FAD) is located in a cleft outside the active site as recently observed in several other p-hydroxybenzoate hydroxylase complexes. Like the native enzyme, a-FAD-containing p-hydroxybenzoate hydroxylase preferentially binds the phenolate form of the substrate (pKo = 7.2). The substrate acts as an effector highly stimulating the rate of enzyme reduction by NADPH (kred &gt; 500 s-1). The oxidative part of the catalytic cycle of a-FAD-containing p-hydroxybenzoate hydroxylase differs from native enzyme. Partial uncoupling of hydroxylation results in the formation of about 0.3 mol of 3,4-dihydroxybenzoate and 0.7 mol of hydrogen peroxide per mol NADPH oxidized. It is proposed that flavin motion in p-hydroxybenzoate hydroxylase is important for efficient reduction and that the flavin "out" conformation is associated with the oxidase activity.

1PDH is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_fluorescens Pseudomonas fluorescens] with <scene name='pdbligand=FAS:'>FAS</scene> and <scene name='pdbligand=PHB:'>PHB</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/4-hydroxybenzoate_3-monooxygenase 4-hydroxybenzoate 3-monooxygenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.14.13.2 1.14.13.2] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PDH OCA].  

[[Category: Berkel, W J.H Van.]]

[[Category: Eppink, M H.M.]]

[[Category: Schreuder, H A.]]

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