Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-072X
    Keywords: Fungal chitin synthetase ; Inhibitors of chitin synthetase ; Nikkomycin Z ; Nikkomycin X ; Polyoxin A ; K i values ; MIC values ; Mucor rouxii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of the nucleoside-peptide antibiotics nikkomycin Z, nikkomycin X, and polyoxin A was tested on chitosomal chitin synthetase from yeast cells of the dimorphic fungus Mucor rouxii. The K i was 0.6 μM for polyoxin A and 0.5 μM for nikkomycin X; nikkomycin Z was slightly less inhibitory (K i=3.5μM). Whereas the minimum inhibitory concentrations of the nikkomycins for growth and germination were quite low (about 1μM, or lower), polyoxin A displayed no antifungal activity against yeast cells and sporangiospores of the test organism, even when present in high concentrations. These results are discussed with respect to structure/activity relationships.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 57 (1967), S. 392-405 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung In Gegenwart von ATP, Mn2ü (oder Mg2ü), CoA und Glutathion fixieren zellfreie Extrakte aus Sporophoren von Agaricus bisporus selbst in Abwesenheit exogener CO2-Acceptoren in erheblichem Maße Kohlendioxyd. Entsprechend der Hemmbarkeit dieser CO2-Fixierungsreaktionen durch Avidin und p-Chloromercuribenzoat handelt es sich bei diesen zum mindesten teilweise um durch Biotin-Enzyme katalysierte Vorgänge. Einer der endogenen CO2-Acceptoren ist sehr washrscheinlich mit aus Isovaleriansäure gebildetem β-Methylcrotonyl-CoA identisch. Die experimentellen Ergebnisse werden im Zusammenhang mit den bekannten physiologischen Effekten von CO2 auf Fruktifikation und Morphogenese des Kulturchampignons diskutiert. Es scheint, daß Biotin-abhängige Carboxylierungsreaktionen eine der biochemischen Grundlagen für den Kontrolleinfluß von Kohlendioxyd im Lebenscyclus von A. bisporus darstellen.
    Notes: Summary Cell-free extracts of sporophores of Agaricus bisporus incorporate considerable amounts of carbon dioxide into organic acids even without added substrate, provided that ATP, Mn2ü or Mg2ü, Coenzyme A and glutathione are present. These CO2-fixation reactions are inhibited by avidin and p-chloromercuribenzoate. It is therefore concluded that at least part of these reactions are katalyzed by biotin enzymes. One of the endogenous CO2-acceptors is probably identical with β-methylerotonyl-CoA, formed from isovaleric acid. The experimental results are diseussed in relation to the well-known physiological effects of carbon dioxide on fructification and morphogenesis in the cultivated mushroom. It is suggested that biotin-dependent carboxylations might represent the biochemical basis for the centrolling function of CO2 in the life cycle of A. bisporus.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 58 (1967), S. 339-356 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Aceton stimuliert die Inkorporation von H14CO3 - in organische Säuren durch zellfreie Extrakte von Agaricus bisporus. Als Endprodukte dieser CO2-Fixierung treten radioaktives Malat, Fumarat sowie Aspartat auf, und zwar unabhängig davon, ob H14CO3 - oder 1,3-14C-Aceton als Tracer verwendet wird. Beim eigentlichen Carboxylierungsprodukt handelt es sich sehr wahrscheinlich um Acetessigsäure. 2. Da die Inkorporation von 14CO2 im Acetonsystem die Gegenwart von ATP, Mg2+, CoA sowie GSH erfordert und durch Avidin und pCMB eine starke Hemmung erfährt, muß die Carboxylierung von Aceton zum mindesten indirekt von einem Biotinenzym abhängig sein. 3. Der Kulturchampignon enthält, wie hier erstmals gezeigt, eine Acetacetatdecarboxylase. Es werden mögliche Ursachen der beim Fruktifikationsbeginn auftretenden Ketogenese diskutiert.
    Notes: Summary 1. Acetone is shown to stimulate the incorporation of bicarbonate into organic acids by cell-free extracts of Agaricus bisporus. Radioactive malate, fumarate and aspartate were determined as end products of this CO2-fixation, regardless whether H14CO3 - or 1,3-14C-acetone was used as a tracer. Acetoacetate is an intermediate in the reaction sequence leading from acetone to these acids, an observation that indicates a carboxylation of the ketone. 2. The incorporation of HCO3 - mentioned above requires the presence of ATP, Mg2+, CoA and GSH; it is inhibited by avidin and pCMB. It is therefore suggested that the carboxylation of acetone depends on biotin, at least in an indirect manner. 3. The presence of acetoacetate decarboxylase in the common mushroom is shown and possible reasons for ketosis as occuring in the first phase of fruiting are discussed.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 65 (1969), S. 195-207 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Zellfreie Extrakte aus Fruchtkörpern von Agaricus bisporus katalysieren eine NADPH-abhängige Reduktion freier Fructose zu Mannitol. In vivo werden neben diesem Zucker auch andere Monosen in den Hexit eingebaut; die entsprechenden Inkorporationsraten sind jedoch gering (für Mannose 11%, Glucose 7% und Xylose 2%, bezogen auf diejenige von Fructose = 100%). Auch die Mannitolbildung aus Glucose erfolgt über Fructose als Zwischenprodukt, und ein alternativer Syntheseweg, Reduktion von Glucose zu Sorbitol und dessen Epimerisierung zu Mannitol beinhaltend, scheint nicht realisiert zu werden, obschon es gelang, Spuren von Sorbitol gaschromatographisch nachzuweisen. Im Kulturchampignon ist demnach freie Fructose als obligater Präkursor von Mannitol zu betrachten. Die experimentellen Resultate werden im Zusammenhang mit unseren gegenwärtigen Kenntnissen über den Kohlenhydratstoffwechsel von A. bisporus diskutiert.
    Notes: Summary In cell-free extracts of fruiting bodies of A. bisporus mannitol is shown to be synthesized by a NADPH-dependent reduction of free fructose. In vivo other monoses are also incorporated into the mannitol skeleton, but to a much lesser extent. Formation of this hexitol from glucose proceeds through fructose as an intermediate, whereas mannitol synthesis by a pathway involving reduction of glucose to sorbitol and epimerization of the latter to the polyol in question does not seem to occur, although it was shown that sorbitol exists in the common mushroom. Therefore, fructose would appear to be the obligate precursor of mannitol in this fungus. The experimental results are integrated into the picture of our present knowledge of carbohydrate metabolism in A. bisporus.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Zellfreie Extrakte aus Agaricus bisporus bilden Malat, Fumarat und Aspartat einerseits aus Pyruvat und CO2 in Gegenwart von Mn2+ und andererseits aus Phosphoenolpyruvat und CO2 in Gegenwart von Mg2+. Die Carboxylierung von Pyruvat wird durch ATP und NADPH2 deutlich gefördert, ist aber unabhängig von der Anwesenheit von CoA-Estern. Die Reaktion erfährt durch pCMB, Oxalat und Avidin eine Hemmung. Die Carboxylierung von Phosphoenolpyruvat wird durch ADP, nicht aber durch GDP und IDP gefördert. Aus den Ergebnissen wird geschlossen, daß bei der Carboxylierung von Pyruvat sowohl Pyruvatcarboxylase als auch Malatenzym wirksam sind, während für die Oxalacetatsynthese aus Phosphoenolpyruvat PEP-Carboxykinase verantwortlich ist. Die Bedeutung der drei Enzyme im Zusammenhang mit der Ernährung des Kulturchampignons aus dem natürlichen Substrat, mit der Glucogenese und der Steuerung des Citronensäurecyclus wird diskutiert.
    Notes: Summary Cell-free extracts from Agaricus bisporus catalyze the synthesis of malate, fumarate and aspartate from pyruvate and CO2 in the presence of Mn2+, and from phosphoenolpyruvate and CO2 with Mg2+ (partially replaceable by Mn2+). The carboxylation of pyruvate is highly stimulated by ATP and NADPH2, but is not affected by CoA-esters. The reaction is inhibited by pCMB, oxalate and avidin. The carboxylation of phosphoenolpyruvate is stimulated by ADP, but not by IDP and GDP. From cofactor-requirement and inhibitor studies it is concluded, that there are two enzymes, pyruvatecarboxylase and malic enzyme, which catalyze the carboxylation of pyruvate. Phosphoenolpyruvate carboxykinase is responsible for the CO2-fixation into oxaloacetate. The significance of these three enzymes is discussed in connection with the nutrition of the fungus from its natural growth substrate and with the regulation of glycogenesis and the citric acid cycle.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 27 (1971), S. 886-888 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The composition of the volatile fractions (isolated by acidic steam distillation) of the spores, substrate mycelium and fruiting body of the common mushroom is investigated. The physiological and/or biochemical functions of some of the identified substances are discussed.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Using Mucor rouxii, the chitin synthase (ChS)-inhibitory and antifungal activity was determined of 6 nucleoside-peptide antibiotics (NPAs) representing pairs of structural analogues, each consisting of a dipeptide (DP) and a corresponding tripeptide (TP). These were the nikkomycins X and I (X, I), the nikkomycins Z and J (Z, J), and the polyoxins D and A (D, A). Although all were very good ChS-inhibitors (X and A being best, with Ki approx. 0.5 μM), only X and Z elicited a strong response in vivo as determined by the degree of inhibition exerted on N-acetylglucosamine (GlcNAc) incorporation into the chitin fraction, the survival rate, and the minimum inhibitory concentration (MIC). The MIC values were about 2 μM (for X and Z) and 100 μM (for I, J, D and A). Certain DPs and TPs reduced the antifungal activity of X, the effect being much more pronounced with DPs. It is suggested that uptake of NPAs involves the transpeptidase reaction of the γ-glutamyl cycle, the observed antagonism thus resulting from competition for a common carrier.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Chemical and enzymological analyses have been carried out to study the mode of action of CO2, in inhibiting germination in Agaricus bisporus and to test the suggestion (Vogel and Weaver, 1972. Exp. Cell Res. 75: 95, Vogel et at, 1974. Am. J. Pathol. 76: 165) that γ-glutaminyl-4-hydroxybenzene (GHB) and/or γ-glutaminyl-3,4-benzoquinone (GBQ) would inhibit the succinate dehydrogenase (SDH) in the mushroom spore and thus represent the causal agent(s) of its dormancy. Evidence is presented that the impairment of SDH is brought about by Ihe CO, fixation product oxaloacelate which is formed in the pyruvate carboxylase reaction, and a mechanism is proposed for the release of the SDH inhibition when activating the spores. These are almost devoid of GHB, whereas fruit bodies of all developmental stages contain considerable amounts of the phenol. GBQ is absent in the spore, and its occurrence in mushroom fruit body extracts appears to be an artifact of extraction. Apart from these analytical results, theoretical reasons are given that vouch against the involvement of the phenolics in the inhibition of SDH in vivo.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1432-2048
    Keywords: Malic enzyme (purification, characterization ; Vilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Malic enzyme (ME=L-malate: NADP oxidoreductase; E.C. 1.1.1.40) was extracted by Triton X-100-induced resolubilization of enzyme proteins which denaturize spontaneously upon homogenization of grape berry material. The purification procedure included fractionating with (NH4)2SO4, preparative IEF, and Sephadex G-100 chromatography. ME was identified by TLC of the radioactive product after supplementing the assay mixture with [14C]malate. Cofactor dependence, pH-optimum and affinities for substrates and cosubstrates were determined. Enzymic pI was found to be 5.8, the Hill coefficients range from 1 to 3. In malate decarboxylating direction at pH 7.4, grape ME displayed positive cooperativity toward the substrate, the curve approaching normal Michaelis-Menten-kinetics at pH 7.0. Substituting Mn2+ for Mg2+ not only increased maximal turnover rates, but also enzymic affinity for malate. These features were considered indicative of the regulatory properties of the enzyme. Their relevance for grape malate metabolism and fruit ripening is discussed.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Planta 80 (1968), S. 154-158 
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Hyperosid (quercetin-3-galactoside) was isolated from the bracts of the dove tree and identified by paper chromatography, melting point determinations, UV- and IR-spectroscopy. The yield of crystalline hyperosid was approximately 1% of the dry weight. It is the main glycoside of the bracts and also appears in the green leaves, but is absent in the bark, wood and fruit. Quercitrin (quercetin-3-rhamnoside) is also present, in minor amount. No other flavonol glycoside could be detected. The analytical results are discussed in relation to their possible taxonomic and physiological implications.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...