Search results for "Alcohol dehydrogenase"
showing 10 items of 35 documents
Effect of ADH II Deficiency on the Intracellular Redox Homeostasis in Zymomonas mobilis
2011
Mutant strain of the facultatively anaerobic, ethanol-producing bacteriumZymomonas mobilis, deficient in the Fe-containing alcohol dehydrogenase isoenzyme (ADH II), showed impaired homeostasis of the intracellular NAD(P)H during transition from anaerobic to aerobic conditions, and also in steady-state continuous cultures at various oxygen supplies. At the same time, ADH II deficiency in aerobically grown cells was accompanied by a threefold increase of catalase activity and by about 50% increase of hydrogen peroxide excretion. It is concluded that ADH II under aerobic conditions functions to maintain intracellular redox homeostasis and to protect the cells from endogenous hydrogen peroxide.
Localization of Lactococcus lactis ssp lactis bv diacetylactis in alginate gel beads affects biomass density and synthesis of several enzymes involve…
1993
Lactococcus lactis ssp lactis bv diacetylactis, immobilized in calcium alginate beads, was grown in synthetic medium in a continuous flow reactor. Cell distribution inside the gel, as well as the activity of various enzymes, was measured after 30 h of operation. The included biomass tended to concentrate at the periphery of the bead along a section of radius about 100 μm long. ATPase activity was maximal in this zone. The activity of NADH oxidase, alcohol dehydrogenase, diacetyl reductase and acetoin reductase, which are repressed in the presence of citrate, were higher in the deeper zones than at the surface of the beads. This result shows that only the peripheral zone of the bead is respo…
Encapsulation of Alcohol Dehydrogenase in Mannitol by Spray Drying
2014
The retention of the enzyme activity of alcohol dehydrogenase (ADH) has been studied in various drying processes such as spray drying. The aim of this study is to encapsulate ADH in mannitol, either with or without additive in order to limit the thermal denaturation of the enzyme during the drying process. The retention of ADH activity was investigated at different drying temperatures. When mannitol was used, the encapsulated ADH was found inactive in all the dried powders. This is presumably due to the quick crystallization of mannitol during spray drying that resulted in the impairment of enzyme protection ability in comparison to its amorphous form. Maltodextin (dextrose equivalent = 11)…
Drug-metabolizing enzymes in the skin of man, rat, and pig.
2007
The mammalian skin has long been considered to be poor in drug metabolism. However, many reports clearly show that most drug metabolizing enzymes also occur in the mammalian skin albeit at relatively low specific activities. This review summarizes the current state of knowledge on drug metabolizing enzymes in the skin of human, rat, and pig, the latter, because it is often taken as a model for human skin on grounds of anatomical similarities. However only little is known about drug metabolizing enzymes in pig skin. Interestingly, some cytochromes P450 (CYP) have been observed in the rat skin which are not expressed in the rat liver, such as CYP 2B12 and CYP2D4. As far as investigated most d…
Sucrose medium osmolality as a regulator of anabolic and catabolic parameters inZymomonas culture
1996
This study focuses on the growth of Zymomonas mobilis strain 113 S and its ethanol and levan production under the conditions of increasing sucrose medium osmolality caused by NaCl, KCl, sorbitol or maltose. The increase in medium osmolality (700-1,500 mosml/kg) was accompanied by the inhibition of growth (growth rate, biomass yield) and ethanol production (specific productivity and yield). In contrast, levan synthesis was less affected or even stimulated and, as a consequence, levan specific productivity was increased significantly. A decrease in the anabolic growth parameters correlated with a parallel inhibition of glucose-6-P dehydrogenase and alcohol dehydrogenase (isoenzyme ADH II) act…
Polymorphism of Alcohol Dehydrogenase Genes in Alcoholic and Nonalcoholic Individuals from Valencia (Spain)
2004
Polymorphisms in the two variable ADH loci (ADH2 and ADH3) were analyzed in two groups (alcoholics and nonalcoholics) from a Spanish population. The frequencies were similar to those reported for other Causcasian groups. ADH2-1 and ADH3-1 genotypes were more frequent in alcoholics than in nonalcoholics, but the differences were not significant.
Enzymes for the NADPH-dependent reduction of dihydroxyacetone and D-glyceraldehyde and L-glyceraldehyde in the mould Hypocrea jecorina
2006
The mould Hypocrea jecorina (Trichoderma reesei) has two genes coding for enzymes with high similarity to the NADP-dependent glycerol dehydrogenase. These genes, called gld1 and gld2, were cloned and expressed in a heterologous host. The encoded proteins were purified and their kinetic properties characterized. GLD1 catalyses the conversion of d-glyceraldehyde and l-glyceraldehyde to glycerol, whereas GLD2 catalyses the conversion of dihydroxyacetone to glycerol. Both enzymes are specific for NADPH as a cofactor. The properties of GLD2 are similar to those of the previously described NADP-dependent glycerol-2- dehydrogenases (EC 1.1.1.156) purified from different mould species. It is a reve…
Regulatory O 2 tensions for the synthesis of fermentation products in Escherichia coli and relation to aerobic respiration
1997
In an oxystat, the synthesis of the fermentation products formate, acetate, ethanol, lactate, and succinate of Escherichia coli was studied as a function of the O2 tension (pO2) in the medium. The pO2 values that gave rise to half-maximal synthesis of the products (pO0. 5) were 0.2-0.4 mbar for ethanol, acetate, and succinate, and 1 mbar for formate. The pO0.5 for the expression of the adhE gene encoding alcohol dehydrogenase was approximately 0.8 mbar. Thus, the pO2 for the onset of fermentation was distinctly lower than that for anaerobic respiration (pO0.5/= 5 mbar), which was determined earlier. An essential role for quinol oxidase bd in microaerobic growth was demonstrated. A mutant de…
Respiratory behaviour of a Zymomonas mobilis adhB::kan(r) mutant supports the hypothesis of two alcohol dehydrogenase isoenzymes catalysing opposite …
2006
AbstractPerturbation of the aerobic steady-state in a chemostat culture of the ethanol-producing bacterium Zymomonas mobilis with a small pulse of ethanol causes a burst of ethanol oxidation, although the reactant ratio of the alcohol dehydrogenase (ADH) reaction ([NADH][acetaldehyde][H+])/([ethanol][NAD+]) remains above the Keq value. Simultaneous catalysis of ethanol synthesis and oxidation by the two ADH isoenzymes, residing in different redox microenvironments, has been proposed previously. In the present study, this hypothesis is verified by construction of an ADH-deficient strain and by demonstration that it lacks the oxidative burst in response to perturbation of its aerobic steady-s…
Responses of Prunus ferganensis, Prunus persica and two interspecific hybrids to moderate drought stress
2003
Prunus ferganensis (Kost. & Riab) Kov. & Kost, a close relative of the cultivated peach (Prunus persica (L.) Batsch.), is native to arid regions of central Asia and may possess traits valuable for improving drought tolerance of commercial peach varieties. One distinguishing feature of P. ferganensis is its prominent, elongated, unbranched leaf venation pattern, which behaves as a simple recessive trait in segregating populations of P. ferganensis x P. persica hybrids. To understand whether this trait could be used as a marker in breeding for drought tolerance, we investigated the association between leaf morphological and physiological parameters related to drought response in P. ferganensi…