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J. Bacteriol., Jan 1998, 296-302, Vol 180, No. 2
SR Kaschabek, T Kasberg, D Muller, AE Mars, DB Janssen and W Reineke
A purification procedure for a new kind of extradiol dioxygenase, termed
chlorocatechol 2,3-dioxygenase, that converts 3-chlorocatechol productively
was developed. Structural and kinetic properties of the enzyme, which is
part of the degradative pathway used for growth of Pseudomonas putida GJ31
with chlorobenzene, were investigated. The enzyme has a subunit molecular
mass of 33.4 kDa by sodium dodecyl sulfate-polyacrylamide gel
electrophoresis. Estimation of the native Mr value under nondenaturating
conditions by gel filtration gave a molecular mass of 135 +/- 10 kDa,
indicating a homotetrameric enzyme structure (4 x 33.4 kDa). The pI of the
enzyme was estimated to be 7.1 +/- 0.1. The N-terminal amino acid sequence
(43 residues) of the enzyme was determined and exhibits 70 to 42% identity
with other extradiol dioxygenases. Fe(II) seems to be a cofactor of the
enzyme, as it is for other catechol 2,3-dioxygenases. In contrast to other
extradiol dioxygenases, the enzyme exhibited great sensitivity to
temperatures above 40 degrees C. The reactivity of this enzyme toward
various substituted catechols, especially 3-chlorocatechol, was different
from that observed for other catechol 2,3-dioxygenases. Stoichiometric
displacement of chloride occurred from 3-chlorocatechol, leading to the
production of 2-hydroxymuconate.
Copyright © 1998, American Society for Microbiology
Degradation of chloroaromatics: purification and characterization of a novel type of chlorocatechol 2,3-dioxygenase of Pseudomonas putida GJ31 [In Process Citation]
Chemische Mikrobiologie, Bergische Universitat-Gesamthochschule Wuppertal, Germany.
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