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  • 1
    Electronic Resource
    Electronic Resource
    The substrate specificity of uptake2 in the rat heart (1984)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 328 (1984), S. 164-173 
    Details
    ISSN: 1432-1912
    Keywords: Extraneuronal uptake ; Rat heart ; Catecholamines ; Stereoselectivity ; Substrate specificity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experiments were carried out with hearts isolated from reserpine- and pargyline-pretreated rats; both noradrenaline-metabolizing enzymes and uptake1 were inhibited. Initial rates of extraneuronal uptake were measured after perfusion lasting for 2 min, either in the absence or in the presence of 100 μmol/l O-methyl-isoprenaline, a potent inhibitor of uptake2. 1. The ID50 (i.e., the concentration of unlabelled substance that halves the rate of uptake of a tracer concentration of 3H-(±)-isoprenaline) was determined for a variety of agents. Two types of stereoselective preference of (-)-isomers were observed: for isoprenaline and adrenaline (but not for noradrenaline)-and also for dobutamine. 2. The stereoselective preference for the (-)-isomers of isoprenaline and adrenaline is also evident from fluorimetric determination of initial rates of uptake of unlabelled isomers. 3. Experiments with various tritiated compounds indicate that uptake2 has a broad substrate spectrum: uptake2 is not restricted to 3H-catecholamines and 3H-phenethylamines, but extends to resorcinols (3H-orciprenaline), imidazoline derivatives (3H-clonidine), 3H-histamine and 3H-5-hydroxytryptamine (3H-5-HT). 4. Determinations of the V max of uptake2 revealed a correlation between the ID50 and the V max: the higher the ID50, the higher the V max. 5. These results indicate that uptake2 is a carrier-mediated process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00512067
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  • 2
    Electronic Resource
    Electronic Resource
    The handling of five amines by the extraneuronal deaminating system of the rat heart (1988)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 337 (1988), S. 159-163 
    Details
    ISSN: 1432-1912
    Keywords: Extraneuronal monoamine oxidase ; Uptake2 ; Rat heart ; Extraneuronal deaminating system ; Catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The handling of five amines by the extraneuronal deaminating system was studied in perfused hearts of rats (pretreated with reserpine; COMT and neuronal uptake inhibited). Hearts were perfused with 50 nmol/l 3H-noradrenaline for 30 min, in the presence of increasing concentrations of unlabelled (−)-adrenaline, (−)-noradrenaline, dopamine, tyramine and 5-HT. IC50's were determined as those concentrations of unlabelled amines which halved the steady-state rate of deamination of 3H-noradrenaline. After correction for changes in the tissue/medium ratio for 3H-noradrenaline, “half-saturating outside concentrations” were obtained. They increased in the order (−)-adrenaline (15 μmol/l) — tyramine — dopamine — noradrenaline —5-HT (53 μmol/l). The V max for extraneuronal deamination was determined for 3H-(−)-adrenaline, 3H-(−)-noradrenaline and 3H-dopamine, as well as (by HPLC and electrochemical detection) for tyramine and 5-HT. It was low for (−)-adrenaline, intermediate for (−)-noradrenaline, dopamine and 5-HT, high for tyramine. For the three catecholamines the half-saturating outside concentrations of the extraneuronal deaminating system clearly exceeded those for the extraneuronal O-methylating system of the same organ (see Grohmann and Trendelenburg 1985), although the two enzymes appear to co-exist in the same cells, so that the same transport system is involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169243
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  • 3
    Electronic Resource
    Electronic Resource
    Evaluation of thermotolerant yeasts in controlled simultaneous saccharifications and fermentations of cellulose to ethanol (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 34 (1989), S. 189-195 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Simultaneous saccharification and fermentation (SSF) experiments were performed at selected temperatures (37, 41, and 43°C) to obtain comprehensive material balance and performance data for several promising strains of thermotolerant yeast. Parameters measured were ethanol concentration, yeast cell density, and residual sugar and cellulose concentrations. The three yeasts Saccharomyces uvarum, Candida brassicae, and C. lusitaniae and two mixed cultures of Brettanomyces clausenii with S. cerevisiae (mixed culture I) and C. Iusitaniae with S. uvarum (mixed culture II) exhibited rapid rates of fermentation, high ethanol yields, strong viability, or high cellobiase activity. Overall, mixed culture II at 41°C performed better than either component yeast by themselves because it combined a cellobiose fermenting capability with the high ethanol tolerance and rapid glucose fermentation of conventional industrial yeasts. Thus, the mixed cultures provide good initial rates by preventing buildup of cellobiose (a strong inhibitor of enzyme activity) while attaining high ultimate yields of ethanol for high cellulase concentrations. However, C. brassicae and S. uvarum gave similar results to mixed culture II at 37°C.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260340207
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  • 4
    Electronic Resource
    Electronic Resource
    Organosolv pretreatment for enzymatic hydrolysis of poplars: I. Enzyme hydrolysis of cellulosic residues (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 31 (1988), S. 643-649 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aspen (Populus tremuloides) and black cottonwood (Populus trichocarpa) organosolv pulps produced in a wide range of solvent composition (between 30 and 70% by volume of methanol) and catalysts (H2SO4 and H3PO4) such that the cooking liquor pH ≤ 3 are easily digested by enzymes. The total yields of hydrolysis residues (pulps) are in the 40-60% range; the acid-catalyzed delignification followed by enzyme hydrolysis can generate 70-88% of the original six-carbon sugars contained in the wood. Glucomannan and arablnogalactan are dissolved into the pulping liquor in the pH range of 2-4.5. Lower pH (≤3) leads to additional solubilization of six-carbon sugars. These sugars may be fermented directly. From the insoluble hydrolysis residues, 36-41% conversions of wood into fermentable sugars were obtained after enzyme hydrolysis; the starting feedstocks contain 50.8 and 46.6% hexosans, respectively, for aspen and black cotton-wood. The kinetics of enzymatic hydrolysis of cellulose can be formally treated as two simultaneous pseudo-first-order reactions in which fast and slow hydrolyses of cellulose occur. Correlations between the glucan digestibility and the effect of the pretreatment have been made. The higher residual xylan content reduces the amount of the rapidly hydrolyzable glucan fraction and lowers the glucan digestibility. The proposed simple kinetic treatment is very helpful in assessing the effect of the pretreatment on pulp enzyme hydrolyzability.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260310703
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  • 5
    Electronic Resource
    Electronic Resource
    Production of cellulase on mixtures of xylose and cellulose in a fed-batch process (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 211-216 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350213
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