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  • 1
    Electronic Resource
    Electronic Resource
    Morpholine-induced formation of l-alanine dehydrogenase activity in Mycobacterium strain HE5 (1999)
    Springer
    Archives of microbiology 171 (1999), S. 417-423 
    Details
    ISSN: 1432-072X
    Keywords: Key words Alanine dehydrogenase ; Ammonia ; assimilation ; Mycobacterium ; Morpholine degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An NAD-dependent, morpholine-stimulated l-alanine dehydrogenase activity was detected in crude extracts from morpholine-, pyrrolidine-, and piperidine-grown cells of Mycobacterium strain HE5. Addition of morpholine to the assay mixture resulted in an up to 4.6-fold increase of l-alanine dehydrogenase activity when l-alanine was supplied at suboptimal concentration. l-Alanine dehydrogenase was purified to near homogeneity using a four-step purification procedure. The native enzyme had a molecular mass of 160 kDa and contained one type of subunit with a molecular mass of 41 kDa, indicating a tetrameric structure. The sequence of 30 N-terminal amino acids was determined and showed a similarity of up to 81% to that of various alanine dehydrogenases. The pH optimum for the oxidative deamination of l-alanine, the only amino acid converted by the enzyme, was determined to be pH 10.1, and apparent K m values for l-alanine and NAD were 1.0 and 0.2 mM, respectively. K m values of 0.6, 0.02, and 72 mM for pyruvate, NADH, and NH4 +, respectively, were estimated at pH 8.7 for the reductive amination reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050728
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  • 2
    Electronic Resource
    Electronic Resource
    Properties and chemical modification of D-amino acid oxidase from Trigonopsis variabilis (1996)
    Springer
    Archives of microbiology 165 (1996), S. 41-47 
    Details
    ISSN: 1432-072X
    Keywords: Key wordsd-amino acid oxidase ; Trigonopsis ; variabilis ; Chemical modification ; Histidine residues ; Km ; Vmax ; Sulfite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The basic properties of purified d-amino acid oxidase from the yeast Trigonopsis variabilis were investigated. The pH optimum of activity was between pH 8.5 and 9.0, and the native molecular masses of holo- and apo-enzyme were determined to be 170 kDa; higher aggregates corresponded to molecular masses of 320 and 570 kDa. The apparent V max and K m values for different substrates varied between 3.7 to 185 U/mg and 0.2 to 17.3 mM, respectively. The reaction of d-amino acid oxidase with sulfite was followed by the typical spectral modifications of the FAD resembling the reduced enzyme; a K d of 30 μM was calculated for the N(5)-adduct. The red anionic flavin radical of the enzyme was stable; benzoate had no influence on the spectral properties. A complete loss of enzyme activity was observed after chemical modification by the histidine-specific reagent diethyl pyrocarbonate. The inactivation showed pseudo-first-order kinetics, with a second-order rate constant of 13.6 M–1 min–1 at pH 6.0 and 20°C. The addition of a substrate under anoxic conditions led to a substantial protection from inactivation, which indicates a localization of the modified residues close to the active site. The pKa of the reacting group was determined to be 7.7, and the rate of inactivation reached a limiting value of 0.031 min–1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050294
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  • 3
    Electronic Resource
    Electronic Resource
    Tetrahydrofuran degradation by a newly isolated culture of Pseudonocardia sp. strain K1 (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 186 (2000), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: An organism capable to grow aerobically on tetrahydrofuran as sole source of carbon and energy was isolated from a waste water treatment plant. The organism designated as strain K1 was identified as Pseudonocardia sp. by chemotaxonomic and morphological characteristics as well as analysis of the gene encoding the 16S rRNA. The highest binary sequence similarity value of 99.0% was obtained to Pseudonocardia sulfidoxydans and Pseudonocardia hydrocarbonoxydans. Optimal growth with a doubling time of 14 h was observed at a tetrahydrofuran concentration of 20 mM and pH 7.0 at 28°C. Under these conditions the substrate was completely degraded within 72 h. In situ concentrations of up to 60 mM were tolerated by the organism without a significantly increased doubling time. The strain also grew on diethyl ether, polyethylene glycol and on γ-butyrolactone and 4-hydroxybutyrate – two potential intermediates in tetrahydrofuran degradation – as sole carbon and energy source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2000.tb09121.x
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  • 4
    Electronic Resource
    Electronic Resource
    2-Hydroxyisonicotinate dehydrogenase isolated from Mycobacterium sp. INA1 (1998)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 164 (1998), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 2-Hydroxyisonicotinate dehydrogenase from Mycobacterium sp. INA1 was purified 26-fold to apparent homogeneity. The enzyme is involved in isonicotinate degradation by Mycobacterium sp. INA1 and catalyzes the conversion of 2-hydroxyisonicotinate to 2,6-dihydroxypyridine-4-carboxylate. The purified protein exhibited a native molecular mass of 300 kDa and subunits of 97, 31 and 17 kDa, respectively, indicating an α2β2γ2 structure. The absorption spectrum of the homogeneous enzyme was characteristic for an iron/sulfur flavoprotein. 3.8 mol of iron, 3.7 mol of acid labile sulfur, 0.94 mol of FAD and 0.75 mol of molybdenum were determined per mol of protomer. The molybdenum cofactor was identified as molybdopterin cytosine dinucleotide. 2-Hydroxyisonicotinate dehydrogenase was inactivated in the presence of cyanide. According to these basic properties the protein seems to belong to the class of molybdo-iron/sulfur flavoproteins of the xanthine oxidase family.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1998.tb13103.x
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