Abstract
Alcaligenes eutrophus CH34 used benzoate as a sole source of carbon and energy, degrading it through the 3-oxoadipate pathway. All the enzymes required for this degradation were shown to be encoded by chromosomal genes. Catechol 1,2-dioxygenase activity was induced by benzoate, catechol, 4-chlorocatechol, and muconate. The enzyme is most likely a homodimer, with an apparent molecular weight of 76,000 ± 500. According to several criteria, its properties are intermediate between those of catechol 1,2-dioxygenases (CatA) and chlorocatechol 1,2-dioxygenases (ClcA). The determined K m for catechol is the lowest among known catechol and chlorocatechol dioxygenases. Similar K m values were found for para-substituted catechols, although the catalytic constants were much lower. The catechol 1,2-dioxygenase from strain CH34 is unique in its property to transform tetrachlorocatechol; however, excess substrate led to a marked reversible inhibition. Some meta- and multi-substituted catechols behaved similarly. The determined K m (or K i) values for para- or meta-substituted catechols suggest that the presence of an electron-withdrawing substituent at one of these positions results in a higher affinity of the enzyme for the ligand. Results of studies of recognition by the enzyme of various nonmetabolised aromatic compounds are also discussed.
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Received: 20 November 1996 / Accepted: 11 April 1996
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Sauret-Ignazi, G., Gagnon, J., Béguin, C. et al. Characterisation of a chromosomally encoded catechol 1,2-dioxygenase (E.C. 1.13.11.1) from Alcaligenes eutrophus CH34. Arch Microbiol 166, 42–50 (1996). https://doi.org/10.1007/s002030050353
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DOI: https://doi.org/10.1007/s002030050353