The University of Southampton
University of Southampton Institutional Repository

Elucidation of the catalytic mechanisms of the non-haem iron-dependent catechol dioxygenases: synthesis of carba-analogues for hydroperoxide reaction intermediates

Elucidation of the catalytic mechanisms of the non-haem iron-dependent catechol dioxygenases: synthesis of carba-analogues for hydroperoxide reaction intermediates
Elucidation of the catalytic mechanisms of the non-haem iron-dependent catechol dioxygenases: synthesis of carba-analogues for hydroperoxide reaction intermediates
The catalytic mechanisms of the non-haem iron-dependent intradiol and extradiol catechol dioxygenases are thought to involve transient hydroperoxide reaction intermediates, formed by reaction of a catechol substrate with dioxygen. The synthesis of carba-analogues of these intermediates is described in which the hydroperoxide functional group (-OOH) is replaced by a hydroxymethyl group (-CH2OH), and the cyclohexadienone skeleton simplified to a cyclohexanone. Analogues of the "proximal" hydroperoxide in which the hydroxymethyl group was positioned axially with respect to the ring were found to act as reversible competitive inhibitors (K-i 0.7-7.6 mM) for the extradiol enzyme 2,3-dihydroxyphenylpropionate 1,2-dioxygenase (MhpB) from Escherichia coli, whereas analogues in which the hydroxymethyl group was positioned equatorially showed no inhibition. In contrast, assays versus the intradiol-cleaving protocatechuate 3,4-dioxygenase from Pseudomonas sp. showed inhibition only by an analogue containing an equatorial hydroxymethyl group (IC50 9.5 mM). These data support the existence of a proximal hydroperoxide intermediate in the extradiol catechol dioxygenase mechanism, and suggest that the conformation adopted by the hydroperoxide reaction intermediate may be an important determinant in the reaction specificity of the extradiol and intradiol dioxygenases.
2, 3-dihydroxyphenylpropionate 1, 2-dioxygenase, oxidation, rearrangement, alcohols, enzymes
0300-922X
3277-3289
Winfield, C. J.
b89bc6e7-045e-4a7e-9ef6-3de7f878d324
Al-Mahrizy, Z.
12e713f1-d2c4-47fb-8c20-938a0083e1e2
Gravestock, M.
5da4b45c-90fa-4e98-b12d-a2f06ae70c0c
Bugg, T. D. H.
a1d6d985-d7ba-408d-a4d1-9bfa0c0642bf
Winfield, C. J.
b89bc6e7-045e-4a7e-9ef6-3de7f878d324
Al-Mahrizy, Z.
12e713f1-d2c4-47fb-8c20-938a0083e1e2
Gravestock, M.
5da4b45c-90fa-4e98-b12d-a2f06ae70c0c
Bugg, T. D. H.
a1d6d985-d7ba-408d-a4d1-9bfa0c0642bf

Winfield, C. J., Al-Mahrizy, Z., Gravestock, M. and Bugg, T. D. H. (2000) Elucidation of the catalytic mechanisms of the non-haem iron-dependent catechol dioxygenases: synthesis of carba-analogues for hydroperoxide reaction intermediates. Journal of the Chemical Society, Perkin Transactions 1, (19), 3277-3289. (doi:10.1039/b004265j).

Record type: Article

Abstract

The catalytic mechanisms of the non-haem iron-dependent intradiol and extradiol catechol dioxygenases are thought to involve transient hydroperoxide reaction intermediates, formed by reaction of a catechol substrate with dioxygen. The synthesis of carba-analogues of these intermediates is described in which the hydroperoxide functional group (-OOH) is replaced by a hydroxymethyl group (-CH2OH), and the cyclohexadienone skeleton simplified to a cyclohexanone. Analogues of the "proximal" hydroperoxide in which the hydroxymethyl group was positioned axially with respect to the ring were found to act as reversible competitive inhibitors (K-i 0.7-7.6 mM) for the extradiol enzyme 2,3-dihydroxyphenylpropionate 1,2-dioxygenase (MhpB) from Escherichia coli, whereas analogues in which the hydroxymethyl group was positioned equatorially showed no inhibition. In contrast, assays versus the intradiol-cleaving protocatechuate 3,4-dioxygenase from Pseudomonas sp. showed inhibition only by an analogue containing an equatorial hydroxymethyl group (IC50 9.5 mM). These data support the existence of a proximal hydroperoxide intermediate in the extradiol catechol dioxygenase mechanism, and suggest that the conformation adopted by the hydroperoxide reaction intermediate may be an important determinant in the reaction specificity of the extradiol and intradiol dioxygenases.

This record has no associated files available for download.

More information

Published date: 2000
Keywords: 2, 3-dihydroxyphenylpropionate 1, 2-dioxygenase, oxidation, rearrangement, alcohols, enzymes

Identifiers

Local EPrints ID: 19028
URI: http://eprints.soton.ac.uk/id/eprint/19028
ISSN: 0300-922X
PURE UUID: 35e63986-02f0-4419-a9e4-29e262626b4b

Catalogue record

Date deposited: 21 Dec 2005
Last modified: 15 Mar 2024 06:10

Export record

Altmetrics

Contributors

Author: C. J. Winfield
Author: Z. Al-Mahrizy
Author: M. Gravestock
Author: T. D. H. Bugg

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×