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  • CoA ligase  (3)
  • Organic Chemistry  (3)
  • 68.35
  • 2020-2021
  • 1995-1999  (1)
  • 1990-1994  (6)
  • 1960-1964
  • 1
    Electronic Resource
    Electronic Resource
    Wavelength-dependent anisotropy of surface second-harmonic generation from Si(111) in the vicinity of bulk absorption (1994)
    Springer
    Applied physics 58 (1994), S. 111-115 
    Details
    ISSN: 1432-0649
    Keywords: 42.65 ; 68.35
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A wavelength-dependence study of surface second-harmonic generation from Si(111) is presented. Femtosecond laser pulses tuned from 430 nm to 710 nm were used to probe the dispersion characteristics of the nonlinear response from the surface in the vicinity of bulk absorption. Changes in the rotational symmetry and in the phase of the generated second-harmonic signal were observed. An explanation of the observed changes is given based on a simple anharmonic oscillator model [1]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01082344
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  • 2
    Electronic Resource
    Electronic Resource
    Purification and characterization of phenylacetate-coenzyme A ligase from a denitrifying Pseudomonas sp., an enzyme involved in the anaerobic degradation of phenylacetate (1993)
    Springer
    Archives of microbiology 159 (1993), S. 554-562 
    Details
    ISSN: 1432-072X
    Keywords: Phenylacetate ; CoA ligase ; Phenylacetyl ; CoA ; Anaerobic aromatic metabolism ; Pseudomonas ; Alpha ; Oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The enzyme catalysing the first step in the anaerobic degradation pathway of phenylacetate was purified from a denitrifying Pseudomonas strain KB 740. It catalyses the reaction phenylacetate+CoA+ATP → phenylacetyl-CoA+AMP+PPi and requires Mg2+. Phenylacetate-CoA ligase (AMP forming) was found in cells grown anaerobically with phenylacetate and nitrate. Maximal specific enzyme activity was 0.048 μmol min-1 x mg-1 protein in the mid-exponential growth phase. After 640-fold purification with 18% yield, a specific activity of 24.4 μmol min-1 mg-1 protein was achieved. The enzyme is a single polypeptide with Mr of 52 ±2 kDa. The purified enzyme shows high specificity towards the aromatic inducer substrate phenylacetate and uses ATP preferentially; Mn2+ can substitute for Mg2+. The apparent K m values for phenylacetate, CoA, and ATP are 60, 150, and 290 μM, respectively. The soluble enzyme has an optimum pH of 8.5, is insensitive to oxygen, but is rather labile and requires the presence of glycerol and/or phenylacetate for stabilization. The N-terminal amino acid sequence showed no homology to other reported CoA-ligases. The expression of the enzye was studied by immunodetection. It is present in cells grown anaerobically with phenylacetate, but not with mandelate, phenylglyoxylate, benzoate; small amounts were detected in cells grown aerobically with phenylacetate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249035
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  • 3
    Electronic Resource
    Electronic Resource
    Anaerobic oxidation of phenylacetate and 4-hydroxyphenylacetate to benzoyl-coenzyme A and CO2 in denitrifying Pseudomonas sp. (1993)
    Springer
    Archives of microbiology 159 (1993), S. 563-573 
    Details
    ISSN: 1432-072X
    Keywords: Phenylacetate ; 4-Hydroxyphenylacetate ; Phenylglyoxylate ; Alpha-Oxidation ; Pseudomonas ; Oxidoreductase ; CoA ligase ; Benzoyl-CoA ; Anaerobic aromatic metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Anaerobic degradation of (4-hydroxy)phenylacetate in denitrifying Pseudomonas sp. was investigated. Evidence is presented for α-oxidation of the coenzyme A (CoA)-activated carboxymethyl side chain, a reaction which has not been described. The C6−C2 compounds are degraded to benzoyl-CoA and furtheron to CO2 via the following intermediates: Phenylacetyl-CoA, phenylglyoxylate, benzoyl-CoA plus CO2; 4-hydroxyphenylacetyl-CoA, 4-hydroxyphenylglyoxylate, 4-hydroxybenzoyl-CoA plus CO2, benzoyl-CoA. Trace amounts of mandelate possibly derived from mandelyl-CoA were detected during phenylacetate degradation in vitro. The reactions are catalyzed by (i) phenylacetate-CoA ligase which converts phenylacetate to phenylacetyl-CoA and by a second enzyme for 4-hydroxyphenylacetate; (ii) a (4-hydroxy)-phenylacetyl-CoA dehydrogenase system which oxidizes phenylacetyl-CoA to (4-hydroxy)phenylglyoxylate plus CoA; and (iii) (4-hydroxy)phenylglyoxylate: acceptor oxidoreductase (CoA acylating) which catalyzes the oxidative decarboxylation of (4-hydroxy)phenylglyoxylate to (4-hydroxy)benzoyl-CoA and CO2. (iv) The degradation of 4-hydroxyphenylacetate in addition requires the reductive dehydroxylation of 4-hydroxybenzoyl-CoA to benzoyl-CoA, catalyzed by 4-hydroxybenzoyl-CoA reductase (dehydroxylating). The whole cell regulation of these enzyme activities supports the proposed pathway. An ionic mechanism for anaerobic α-oxidation of the CoA-activated carboxymethyl side chain is proposed. Phenylacetic acids are plant constituents and in addition are formed from a large variety of natural aromatic compounds by microorganisms; their degradation therefore plays a significant role in nature, as illustrated in the preceding paper (Mohamed and Fuchs 1993). We have investigated and purified an enzyme which catalyzes the first step in the anaerobic degradation of phenylacetate in a denitrifying Pseudomonas sp. Phenylacetate is converted to phenylacetyl-CoA by phenylacetate-CoA ligase (AMP forming). The postulated function of this enzyme is corroborated by the strict regulation of its expression. 4-Hydroxyphenylacetate appears to be similarly activated by an independent enzyme prior to further degradation. We have suggested before that phenylacetyl-CoA is anaerobically converted by α-oxidation of the side chain to phenylglyoxylate1, which is oxidatively decarboxylated to benzoyl-CoA plus CO2 (Seyfried et al. 1991; Dangel et al. 1991). 4-Hydroxyphenylacetate was proposed to be similarly oxidized to 4-hydroxybenzoyl-CoA plus CO2, followed by reductive dehydroxylation to benzoyl-CoA. The evidence was not presented in full, and the crucial α-oxidation was not demonstrated in vitro. We present here ample evidence for this pathway. A hypothetical mechanism is proposed by which the oxidation of the α-methylene group to an α-carbonyl group may occur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249036
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  • 4
    Electronic Resource
    Electronic Resource
    Differential induction of enzymes involved in anaerobic metabolism of aromatic compounds in the denitrifying bacterium Thauera aromatica (1998)
    Springer
    Archives of microbiology 170 (1998), S. 120-131 
    Details
    ISSN: 1432-072X
    Keywords: Key words Anaerobic aromatic metabolism ; Benzoyl-CoA reductase ; Phenylphosphate carboxylase ; 4-Hydroxybenzoyl-CoA reductase ; 2-Aminobenzoate ; Phenylalanine ; Phenylacetyl-CoA ; Phenylglyoxylate ; Toluene ; CoA ligase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Differential induction of enzymes involved in anaerobic metabolism of aromatic substrates was studied in the denitrifying bacterium Thauera aromatica. This metabolism is divided into (1) peripheral reactions transforming the aromatic growth substrates to the common intermediate benzoyl-CoA, (2) the central benzoyl-CoA pathway comprising ring-reduction of benzoyl-CoA and subsequent β-oxidation to 3-hydroxypimelyl-CoA, and (3) the pathway of β-oxidation of 3-hydroxypimelyl-CoA to three acetyl-CoA and CO2. Regulation was studied by three methods. 1. Determination of protein patterns of cells grown on different substrates. This revealed several strongly substrate-induced polypeptides that were missing in cells grown on benzoate or other intermediates of the respective metabolic pathways. 2. Measurement of activities of known enzymes involved in this metabolism in cells grown on different substrates. The enzyme pattern found is consistent with the regulatory pattern deduced from simultaneous adaptation of cells to utilisation of other aromatic substrates. 3. Immunological detection of catabolic enzymes in cells grown on different substrates. Benzoate-CoA ligase and 4-hydroxybenzoate-CoA ligase were detected only in cells yielding the respective enzyme activity. However, presence of the subunits of benzoyl-CoA reductase and 4-hydroxybenzoyl-CoA reductase was also recorded in some cell batches lacking enzyme activity. This possibly indicates an additional level of regulation on protein level for these two reductases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050623
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  • 5
    Electronic Resource
    Electronic Resource
    Cyclocondensation of 4-Benzyl-1-hydrazinophthalazine (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 1041-1048 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Hydrazino-4-benzylphthalazine 1 underwent closure and/or condensation reaction with formic acid, acetic acid, acetic anhydride, trifluoroacetic anhydride, ortho esteres, aldehydes, urea or carbon disulphide to afford the N-formyl 3a, N-acyl 3b, and the appropriate 3-substituted-6-benzyl-s-triazolo [3,4-a] phthalazines 4a, c, 7, 8. Alkylation of the obtained s-triazolo[3,4-a]-phthalazine-3-thione 7 and s-triazolo [3,4-a] phthalazin-3-one 8 with N-substituted chloroacetamides gave the thioether 9 and N-substitution products 10, respectively. Likewise, applying Mannich conditions of the previously mentioned intermediates 7 and 8 yielded the N-Mannich bases (11 and 12). The new products were characterized by their elemental and spectral data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320622
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis of polyfunctionally substituted pyridazines (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 293-296 
    Details
    ISSN: 0170-2041
    Keywords: Pyridazine, derivatives ; Pyrazolo-pyridazine, derivative ; Pyrido-pyridazine, derivative ; Isoxazolo-pyridazine, derivative ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyridazines 3, 4, 5, and 7 were obtained by reaction of the hydrazone derivatives 2 with several reagents. By treatment of 5 with acetic acid/hydrochloric acid, the pyrazolo[4,3-c]-pyridazine 6 was formed. The pyrido-pyridazine derivatives 8 and 9 were obtained by reaction of 2 and 3 with malononitrile and ethyl cyanoacetate, respectively, and the isoxazolo-pyridazines 11 by reaction of 3a, b with hydroxylamine hydrochloride in ethanolic sodium ethoxide solution. The intermediate 9 was separated by reaction of 3a, b with hydroxylamine hydrochloride in ethanolic sodium acetate solution.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900153
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis of 2-alkyl-3-vinyloxaziridines as potential antitumor agents (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 461-464 
    Details
    ISSN: 0170-2041
    Keywords: Antitumor agents ; Oxaziridines ; Aldimines, unsaturated ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A convenient method for the synthesis of previously unknown oxaziridines having unsaturated substituents at the 3-position (3a-k) is based on the selective oxidation of the imino group of α,β-unsaturated aldimines 2 with m-chloroperbenzoic acid. The title compounds and 2-tert-butyl-3-(phenylethynyl)oxaziridine (3k) exhibit potent activity against experimental tumor cells in vitro.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900187
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