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Abstract
The aim of the present work was to investigate the influence of alkylhydroxybenzenes (AHBs) and tyrosol, which belong to cell differentiation factors d 1 group of autoregulators on properties of biodegradation enzymes, catechol 1,2-dioxygenase (Cat 1,2-DO) and methylcatechol 1,2-dioxygenase (MCat 1,2-DO) of Rhodococcus opacus 6a. AHBs were found to have a greater effect on MCat 1,2-DO than on Cat 1,2-DO. It was expressed by more pronounced changes in the activity of MCat 1,2-DO with unsubstituted catechol at different AHB concentrations and by increasing thermostability of MCat 1,2-DO compared to Cat 1,2-DO under the protective action of AHBs. The compound C7-AHB shifted the maximum of dioxygenase activities towards higher temperatures and increased their operation optimum. AHBs changed the specificity constant of dioxygenases by decreasing/increasing the K m/V max value. For example, the increase in the V max value of 3,6-dichlorocatechol oxidation by Cat 1,2-DO in the presence of C7-AHB was 300-fold higher compared to the same reaction without AHB. The influence of cell differentiation factors on the properties of dimeric enzymes has been shown for the first time. It gives an idea of how the specificity of enzymes can be changed in vivo when strains contact new substrates. The work has shown the possibility of modification of the properties of dimeric enzymes towards the extension of enzyme activity with difficulty converted substrates or in more extreme conditions, which may be important for biotechnological processes.
Acknowledgments
The work was supported by the Russian Foundation for Basic Research (grant RFBR-Ural_ofi No 07-04-97625).