Faculty of Biology, University of Latvia
Hard copy: ISSN 1691–8088
On-line: ISSN 2255–9582
Acta Univ Latv (2005) 691: 71–81
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Environmental and

Acta Univ Latv (2005) 691: 71–81

Orginal Article

Intracellular redox state regulates the resistance of Zymomonas mobilis alcohol dehydrogenase II to cyanide and oxygen

Uldis Kalnenieks*, Ņina Galiņina, Reinis Rutkis, Malda M. Toma
Institute of Microbiology and Biotechnology, University of Latvia, Kronvalda Bulv. 4, Rīga LV-1586, Latvia
*Corresponding author, E-mail: kalnen@lanet.lv


The variable sensitivity of Zymomonas mobilis iron-containing alcohol dehydrogenase isoenzyme (ADH II) to cyanide and oxygen was studied. The cyanide-sensitivity of ADH II was highest in cells grown under conditions of vigorous aeration, in which intracellular NADH concentration was low. Anaerobically grown bacteria, as well as those cultivated aerobically in the presence of cyanide, maintained a higher intracellular NADH pool along with a more cyanide-resistant ADH II. In aerobically grown permeabilized cells, cyanide caused gradual inhibition of ADH II, which was largely prevented by externally added NADH, and, to lesser extent, by NAD. It was demonstrated that cyanide acted as a competitive inhibitor of ADH II, competing with nicotinamide nucleotides. NADH increased both the cyanide resistance and oxygen resistance of ADH II.

Key words: alcohol dehydrogenase, cyanide resistance, oxygen resistance, Zymomonas mobilis.

Acta Univ Latv (2005) 691: 71–81
 DOI: http://doi.org/10.22364/eeb

Prof. Gederts Ievinsh
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