Developmental and environmental influences in the production of a single NAD-dependent fermentative alcohol dehydrogenase by the zygomycete Mucor rouxii.
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 ( approximately pH 8.5) and for the reduction of acetaldehyde to ethanol (approximately 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, NADH(2), and NAD(+) indicated that physiologically the enzyme works mainly in the reduction of acetaldehyde to ethanol.
Zazueta-Sandoval
R
R
Instituto de Investigación en Biología Experimental, Facultad de Química, Universidad de Guanajuato, Apartado Postal 187, Guanajuato, Gto., 36000, México.
Gutiérrez-Corona
J F
JF
D000332:Aerobiosis; D000426:Alcohol Dehydrogenase / Q000096:biosynthesis* / Q000302:isolation & purification; D000693:Anaerobiosis; D003470:Culture Media; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D009089:Mucor / Q000201:enzymology* / Q000254:growth & development*; D009243:NAD / Q000378:metabolism; D013379:Substrate Specificity
D003470:Culture Media; D009243:NAD; D000431:Ethanol; D000426:Alcohol Dehydrogenase