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1pdh
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(New page: 200px<br /><applet load="1pdh" size="450" color="white" frame="true" align="right" spinBox="true" caption="1pdh, resolution 2.1Å" /> '''CRYSTAL STRUCTURE OF ...)
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Revision as of 21:35, 20 November 2007
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CRYSTAL STRUCTURE OF P-HYDROXYBENZOATE HYDROXYLASE RECONSTITUTED WITH THE MODIFIED FAD PRESENT IN ALCOHOL OXIDASE FROM METHYLOTROPHIC YEASTS: EVIDENCE FOR AN ARABINOFLAVIN
Overview
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 >, 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.
About this Structure
1PDH is a Single protein structure of sequence from Pseudomonas fluorescens with FAS and PHB as ligands. Active as 4-hydroxybenzoate 3-monooxygenase, with EC number 1.14.13.2 Full crystallographic information is available from OCA.
Reference
Crystal structure of p-hydroxybenzoate hydroxylase reconstituted with the modified FAD present in alcohol oxidase from methylotrophic yeasts: evidence for an arabinoflavin., van Berkel WJ, Eppink MH, Schreuder HA, Protein Sci. 1994 Dec;3(12):2245-53. PMID:7756982
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