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1knf

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{{STRUCTURE_1knf| PDB=1knf | SCENE= }}
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'''Crystal Structure of 2,3-dihydroxybiphenyl 1,2-dioxygenase Complexed with 3-methyl Catechol under Anaerobic Condition'''
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===Crystal Structure of 2,3-dihydroxybiphenyl 1,2-dioxygenase Complexed with 3-methyl Catechol under Anaerobic Condition===
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==Overview==
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The steady-state cleavage of catechols by 2,3-dihydroxybiphenyl 1, 2-dioxygenase (DHBD), the extradiol dioxygenase of the biphenyl biodegradation pathway, was investigated using a highly active, anaerobically purified preparation of enzyme. The kinetic data obtained using 2,3-dihydroxybiphenyl (DHB) fit a compulsory order ternary complex mechanism in which substrate inhibition occurs. The Km for dioxygen was 1280 +/- 70 microM, which is at least 2 orders of magnitude higher than that reported for catechol 2,3-dioxygenases. Km and Kd for DHB were 22 +/- 2 and 8 +/- 1 microM, respectively. DHBD was subject to reversible substrate inhibition and mechanism-based inactivation. In air-saturated buffer, the partition ratios of catecholic substrates substituted at C-3 were inversely related to their apparent specificity constants. Small organic molecules that stabilized DHBD most effectively also inhibited the cleavage reaction most strongly. The steady-state kinetic data and crystallographic results suggest that the stabilization and inhibition are due to specific interactions between the organic molecule and the active site of the enzyme. t-Butanol stabilized the enzyme and inhibited the cleavage of DHB in a mixed fashion, consistent with the distinct binding sites occupied by t-butanol in the crystal structures of the substrate-free form of the enzyme and the enzyme-DHB complex. In contrast, crystal structures of complexes with catechol and 3-methylcatechol revealed relationships between the binding of these smaller substrates and t-butanol that are consistent with the observed competitive inhibition.
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{{ABSTRACT_PUBMED_9857017}}
==About this Structure==
==About this Structure==
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[[Category: Dioxygenase]]
[[Category: Dioxygenase]]
[[Category: Oxidoreductase]]
[[Category: Oxidoreductase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul 2 10:35:42 2008''

Revision as of 07:35, 2 July 2008

Template:STRUCTURE 1knf

Crystal Structure of 2,3-dihydroxybiphenyl 1,2-dioxygenase Complexed with 3-methyl Catechol under Anaerobic Condition

Template:ABSTRACT PUBMED 9857017

About this Structure

1KNF is a Single protein structure of sequence from Burkholderia cepacia. Full crystallographic information is available from OCA.

Reference

Molecular basis for the stabilization and inhibition of 2, 3-dihydroxybiphenyl 1,2-dioxygenase by t-butanol., Vaillancourt FH, Han S, Fortin PD, Bolin JT, Eltis LD, J Biol Chem. 1998 Dec 25;273(52):34887-95. PMID:9857017

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