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At least 1,171 records · Page 65Linked to original sources
PubMed2005

A sequential enzymatic microreactor system for ethanol detection of gasohol mixtures.

A sequential enzymatic double microreactor system with dilution line was developed for quantifying ethanol from gasohol mixtures, using a colorimetric detection method, as a new proposal to the single micro reactor system used in previous work. Alcohol oxidase (AOD) and horseradish peroxidase (HRP) immobilized on glass beads, one in each microreactor, were used with phenol and 4-aminophenazone and the red-colored product was detected with a spectrophotometer at 555 nm. Good results were obtained with the immobilization technique used for both AOD and HRP enzymes, with best retention efficiencies of 95.3 +/- 2.3% and 63.2 +/- 7.0%, respectively. The two microreactors were used to analyze extracted ethanol from gasohol blends in the range 1-30 % v/v (10.0-238.9 g ethanol/L), with and without an on-line dilution sampling line. A calibration curve was obtained in the range 0.0034-0.087 g ethanol/L working with the on-line dilution integrated to the biosensor FIA system proposed. The diluted sample concentrations were also determined by gas chromatography (GC) and high-pressure liquid chromatography (HPLC) methods and the results compared with the proposed sequential system measurements. The effect of the number of analysis performed with the same system was also investigated.

Alcohol Oxidoreductases↗
PubMedDate not supplied

Effect of early maternal adrenalectomy on antioxidant enzymes, GSH, ascorbate, and uric acid in the rat fetal lung at term.

Previous studies have shown that the increase of the enzymatic antioxidant defense that takes place in the fetal rat lung at the end of gestation can be accelerated by the synthetic glucocorticoid dexamethasone and diminished by metyrapone, a blocker of glucocorticoid synthesis. Since it is known that the fetal adrenal does not start to synthesize corticosterone until the last 20% of gestation, pregnant rats were bilaterally adrenalectomized on the first day of gestation in order to clarify the role of the endogenous maternal hormone on the development of the enzymatic and nonenzymatic antioxidant systems of fetal lung. This early adrenalectomy did not change fetal lung catalase, glutathione peroxidase, glutathione reductase, cytochrome oxidase, GSH, ascorbate, and uric acid at term. The presence of the maternal glands is not essential for lung antioxidant development in the fetus and that the stimulus of fetal corticosterone during the last 20% of gestation is enough to achieve a normal maturation of the fetal lung enzymatic and nonenzymatic antioxidant systems.

Adrenal Glands↗
PubMedDate not supplied

[Optimization of conditions for cultivation of the basidiomycete Coriolus hirsutus--producer of extracellular laccase].

The effects of various factors on the biosynthesis of extracellular laccase (EC 1.14.18.1) by the basidiomycete Coriolus hirsutus (Wulf.: Fr.) Quel. no. 072 during submerged cultivation were examined. Optimal parameters for cultivation in a fermenter of 10 l were determined: temperature, 28 degrees C; stirrer rotation speed, 160 rpm; and the inoculum volume, 15% of the working volume of the fermenter. The filtrate contained peroxidase, laccase, and phenol oxidase activities and displayed a high thermal stability.

Basidiomycota↗
PubMedDate not supplied

[Deamination of nitrogenous compounds in mitochondrial membranes under stimulation of lipid peroxidation].

Fragments of mitochondrial membranes, obtained by freezing-thawing of mitochondrial fraction from rat liver homogenate, were treated with Fe2+ ions under conditions, which were optimal for accumulation of a product of lipid peroxidation--malondialdehyde (MDA). The accumulation of MDA in the mitochondrial membranes was accompanied by a decrease in deamination of monoamines (tyramine or, especially, tryptamine) and by appearance of qualitatively new properties to deaminate histamine or cadaverine as well as adenylic acid. Appearance of these properties was prevented by blocking with trans-2-phenylcyclopropylamine or N-methyl-N-benzylpropynylamine of the mitochondrial monoamine oxidase activity. Inhibitors of initiated by free radicals lipid peroxidation (propylgallate, butyl hydroxytoluene) did not bind Fe2+ ions but prevented the alterations in deamination of nitrogenous compounds induced by the treatment of the fragments of mitochondrial membranes with Fe2+ ions. Stimulation of lipid peroxidation in mitochondrial membranes was, thus, accompanied not only by partial inactivation of the structure-bound monoamine oxidase but also by apparent qualitative alteration (transformation) in its catalytic properties.

Animals↗