Developmental and environmental influences in the production of a single NAD-dependent fermentative alcohol dehydrogenase by the zygomycete Mucor rouxii |
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Authors: | Roberto Zazueta-Sandoval J Félix Gutiérrez-Corona |
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Institution: | (1) Instituto de Investigación en Biología Experimental, Facultad de Química, Universidad de Guanajuato, Apartado Postal 187, Guanajuato, Gto., 36000, México e-mail: felixg@quijote.ugto.mx, Tel.: +52-473-24302, Fax: +52-473-24302, XX |
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Abstract: | A soluble NAD-dependent alcohol dehydrogenase (ADH) activity was detected in mycelium and yeast cells of wild-type Mucor rouxii. In the mycelium of cells grown in the absence of oxygen, the enzyme activity was high, whereas in yeast cells, ADH activity
was high regardless of the presence or absence of oxygen. The enzyme from aerobically or anaerobically grown mycelium or yeast
cells exhibited a similar optimum pH for the oxidation of ethanol to acetaldehyde (∼pH 8.5) and for the reduction of acetaldehyde
to ethanol (∼pH 7.5). Zymogram analysis conducted with cell-free extracts of the wild-type and an alcohol-dehydrogenase-deficient
mutant strain indicated the existence of a single ADH enzyme that was independent of the developmental stage of dimorphism,
the growth atmosphere, or the carbon source in the growth medium. Purified ADH from aerobically grown mycelium was found to
be a tetramer consisting of subunits of 43 kDa. The enzyme oxidized primary and secondary alcohols, although much higher activity
was displayed with primary alcohols. K
m values obtained for acetaldehyde, ethanol, NADH2, and NAD+ indicated that physiologically the enzyme works mainly in the reduction of acetaldehyde to ethanol.
Received: 11 March 1999 / Accepted: 14 July 1999 |
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Keywords: | Alcohol dehydrogenase Mucor rouxii Yeast/mold dimorphism Developmental/environmental regulation |
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