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  • 1
    Electronic Resource
    Electronic Resource
    Identification of Serine-143 as the Most Likely Precursor of Dehydroalanine in the Active Site of Histidine Ammonia-lyase. A study of the Overexpressed Enzyme by Site-Directed Mutagenesis (1994)
    s.l. : American Chemical Society
    Biochemistry 33 (1994), S. 6462-6467 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00187a011
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  • 2
    Electronic Resource
    Electronic Resource
    Histidine Ammonia-Lyase Mutant S143C Is Posttranslationally Converted into Fully Active Wild-Type Enzyme. Evidence for Serine 143 To Be the Precursor of Active Site Dehydroalanine (1994)
    s.l. : American Chemical Society
    Biochemistry 33 (1994), S. 14034-14038 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00251a011
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  • 3
    Electronic Resource
    Electronic Resource
    Nature of coenzyme binding by glyceraldehyde-3-phosphate dehydrogenase: carbon-13 NMR studies with oxidized [4-13C]nicotinamide adenine dinucleotide (1989)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 111 (1989), S. 4440-4447 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00194a045
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanistic aspects of molybdenum-containing enzymes (1998)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 22 (1998), S. 0 
    Details
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6976.1998.tb00383.x
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  • 5
    Electronic Resource
    Electronic Resource
    A structural comparison of molybdenum cofactor-containing enzymes (1998)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 22 (1998), S. 0 
    Details
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: This work gives an overview of the recent achievements which have contributed to the understanding of the structure and function of molybdenum and tungsten enzymes. Known structures of molybdo-pterin cofactor-containing enzymes will be described briefly and the structural differences between representatives of the same and different families will be analyzed. This comparison will show that the molybdo-pterin cofactor-containing enzymes represent a very heterogeneous group with differences in overall enzyme structure, cofactor composition and stoichiometry, as well as differences in the immediate molybdenum environment. Two recently discovered molybdo-pterin cofactor-containing enzymes will be described with regard to molecular and EPR spectroscopic properties, pyrogallol-phloroglucinol transhydroxylase from Pelobacter acidigallici and acetylene hydratase from Pelobacter acetylenicus. On the basis of its amino acid sequence, transhydroxylase can be classified as a member of the dimethylsulfoxide reductase family, whereas classification of the tungsten/molybdenum-containing acetylene hydratase has to await the determination of its amino acid sequence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6976.1998.tb00384.x
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  • 6
    Electronic Resource
    Electronic Resource
    Superoxide inhibition following different stimuli of respiratory burst and metabolism of aminosalicylates in neutrophils (1994)
    Springer
    Digestive diseases and sciences 39 (1994), S. 145-151 
    Details
    ISSN: 1573-2568
    Keywords: superoxide radicals ; inhibition ; 5-aminosalicylic acid ; 4-aminosalicylic acid ; benzalazine ; olsalazine ; lipopolysaccharide ; N-acetylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Reactive oxygen species such as superoxide radicals have been proposed to play an important role in the pathogenesis of inflammatory bowel disease. Some of the antiinflammatory actions of aminosalicylates have been ascribed to their capability to scavenge superoxide radicals directly or to inhibit its production in stimulated neutrophils. However, as a controversy still exists with regard to the precise mechanisms of inhibition and the metabolism within inflammatory cells, we compared scavenger properties of 5-aminosalicylic acid, 4-aminosalicylic acid,N-acetyl aminosalicylic acid, olsalazine, and benzalazine in systems with defined superoxide radical generation such as the dimethyl sulfoxide-NaOH and the potassium superoxide system. We also studied possible inhibition of the superoxide production following different stimuli of the respiratory burst in neutrophils and investigated the uptake and potential metabolism (N-acetylation) of 5-aminosalicylic acid in lipopolysaccharide-primed and resting neutrophils. We found that 5-aminosalicylic acid and 4-aminosalicylic acid had defined scavenger properties in the dimethyl sulfoxide-NaOH or potassium superoxide systems, respectively, whereas compounds with a modified aminophenolic structure had no effects. At the cellular level, 5-aminosalicylic acid inhibited phorbol myristate acetate (100 ng/ml)-activated superoxide generation to 82.3±9.3%, the formylmethionyl leucyl peptide (10−5 M) to 61.0±6.8%, and the NaF (20 mM) -stimulated production to 32.3±3.2% (X±sd,P〈0.01). The actions of the other drugs were less pronounced. Almost identical retention times (R t=11.2 min) of3H-labeled phorbol myristate acetate in the presence and absence of 5-aminosalicylic acid revealed noin vitro interactions. 5-Aminosalicylic acid permeates cells in a dose- and time-dependent manner; there was, however, no acetylation of 5-aminosalicylic acid regardless whether the cells had been stimulated or not with lipopolysaccharide. From our results we suggest that (1) the extra- (scavenger) and intracellular inhibition of superoxide radicals by 5-aminosalicylic acid may be an important mechanism of action, (2) an intact aminophenolic structure may be necessary for such actions, and (3) the inability of inflammatory neutrophils to acetylate and, therefore, inactivate 5-aminosalicylic acid could be an important determinant for its local actions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02090074
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis and Reactions of a Chemical Model of the Urocanase ReactionDedicated to the memory of Wolfgang Oppolzer (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 410-416 
    Details
    ISSN: 0947-6539
    Keywords: enzyme catalysis ; nicotinamide-adenine dinucleotide ; reaction mechanisms ; urocanase ; urocanic acid ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using a convergent synthetic strategy starting from nicotinic acid and imidazole, we have prepared the (E) and (Z) isomers of 1-benzyl-3-carbamoyl-5-[2-(ethoxycarbonylmethylene)-2-(1-(p-to-lylsulfamoyl)imidazol-4-yl)ethyl]pyridinium bromide (21) as models of the urocanase reaction. Domino reactions of both (E)-21 and (Z)-21 led to the same spirocyclic compound, (3aRS)-11-[9-([D7]benzyl)-5-ethoxy-1-(p-tolylsulfamoyl)-1H,9H-furo[2,3-g]imidazo[5,4-f]isoquinolyl]carboxamide (33), which was isolated and spectroscopically characterised. A possible sequence of reactions leading to 33 shows a number of analogies to the conversions catalysed by the enzyme urocanase. Removal of the p-tolylsulfamoyl protecting group of (E)-21 and (Z)-21 under mild conditions led to the highly reactive model compounds (E)-4 and (Z)-4, which were identified by 1H NMR spectroscopy, but could not be isolated, owing to their instability. To facilitate the monitoring of the reaction cascade by NMR spectroscopy (Z)-21 was prepared in which the benzyl group was fully deuterated. Its deprotection to (Z)-4 started a reaction cascade, which led, after purification, to a main product. According to investigations by UV and 1H NMR spectroscopy it seems very likely that 1-([D7]benzyl)-3-carbamoyl-7-(ethoxycarbonylmethyl)-imidazo[4,5-f]isoquinolinium bromide (27) was formed. The presumed mechanism of its formation again shows similarities with the postulated mechanism of action of urocanase.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030312
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  • 8
    Electronic Resource
    Electronic Resource
    Cholestano-cobaloxime und Cholestano-rhodoxime. Synthese, Charakterisierung und Umlagerung von Modellverbindungen für die Aktivstelle von Methylmalonyl-CoA-Mutase (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 650-668 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparative, Spectroscopic, and Crystallographic Investigations on Phosphinato Complexes of Rhenium with Bidentate Nitrogen LigandsCholestano-cobaloximes and cholestano-rhodoximes, three diastereoisomers of each constitution, were synthesised from cholestane-2,3-dione dioxime (3). The diastereoisomeric complexes were separated and characterised by their spectra. One of the axial ligands was invariably pyridine, the other either chlor (9), methyl (10), 2,2-bis(methoxycarbonyl)propyl (11), 2,2-bis(benzyl-oxycarbonyl)propyl (12), or 2,2-bis(2-naphthylmethoxycarbonyl)propyl (13 and 14). Irradiation of the complexes 11, 12, 13, and 14 in ethanol or 2-propanol afforded, apart from dimethylmalonic diester, other products among which was the corresponding methylsuccinic diester in yields of approx. 1, 20, 23, and 13%, respectively. The methylsuccinic acid bis(2-naphthylmethyl ester) obtained from the irradiation of the diastereoisomeric cholestano-cobaloximes 13a, b and c was found to be practically racemic.
    Notes: Aus Cholestan-2,3-dion-dioxim (3) wurden jeweils drei diastereomere Cholestano-cobaloxime und Cholestano-rhodoxime synthetisiert, die getrennt und spektroskopisch charakterisiert wurden. Pyridin diente durchweg als einer der axialen Liganden, der andere war Chlor (9), Methyl (10), 2,2-Bis(methoxycarbonyl)propyl (11), 2,2-Bis(benzyloxycarbonyl)propyl (12) oder 2,2-Bis(2-naphthylmethoxycarbonyl)propyl (13 und 14). Bestrahlung der Komplexe 11, 12, 13 und 14 in Ethanol oder 2-Propanol gab neben den Dimethylmalonsäureestern und weiteren Produkten auch die entsprechenden Methylbernsteinsäure-diester in Ausbeuten von etwa 1, 20, 23 und 13%. Der aus den diastereomeren Cholestano-cobaloximen 13a, b und c erhaltene Methylbernsteinsäure-bis(2-naphthylmethylester) war praktisch racemisch.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19801130223
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  • 9
    Electronic Resource
    Electronic Resource
    Sterischer Verlauf der Substitution am Cyclopropangerüst durch Cobal(I)oxim Synthese und Charakterisierung von Cyclopropylcobaloximen (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2229-2241 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Steric Course of the Substitution at the Cyclopropane Skeleton by Cobal(I)oxime. Synthesis and Characterisation of Cyclopropylcobaloximes7,7-Dibromodibenzo[b,d]norcaradiene (1) as well as exo- and endo-7-bromodibenzo[b,d]norcaradiene (2a and b) were synthesized and reacted with cobal(I)oxime. (7-Bromodibenzo[b,d]norcaradien-7-yl)(pyridine)cobaloxime (5) was formed from 1 beside some (dibenzo[b,d]norcaradien-7-yl)(pyridine)cobaloxime (6) and (dibenzo[a,c]cycloheptatrien-6-yl)(pyridine)cobaloxime (4), whereas the reaction of 2a yielded 6 as the sole alkylcobaloxime. Under the same conditions 2b was inert. 4-6 were characterized by X-ray crystallography and spectroscopic methods. The substitution in 2a took place with retention, whereas the analogous substitution in the two enantiomeric 1-bromo-1-methyl-2,2-diphenylcyclopropanes (8a and b) occured with racemisation. This shows that the observed retention was caused merely by steric effects and that cyclopropyl radical intermediates occurred in both cases.
    Notes: 7,7-Dibromdibenzo[b,d]norcaradien (1) sowie exo- und endo-7-Bromdibenzo[b,d]norcaradien (2a und b) wurden synthetisiert und mit Cobal(I)oxim umgesetzt. Aus 1 erhielt man (7-Bromdibenzo[b,d]norcaradien-7-yl)(pyridin)cobaloxim (5) neben (Dibenzo[b,d]norcaradien-7-yl)(pyridin)cobaloxim (6) und (Dibenzo[a,c]cycloheptatrien-6-yl)(pyridin)cobaloxim (4), während aus 2a als einziges Alkylcobaloxim 6 gebildet wurde. 2b war unter denselben Reaktionsbedingungen inert. 4-6 wurden durch Röntgenstrukturanalyse und Spektren charakterisiert. Die Substitution an 2a erfolgte unter Retention, die analoge Substitution an den beiden enantiomeren 1-Brom-1-methyl-2,2-diphenylcyclopropanen (8a und b) dagegen unter Racemisierung. Dies zeigt, daß die im ersten Fall beobachtete Retention lediglich sterischen Effekten zuzuschreiben ist und in beiden Fällen eine freie Cyclopropyl-Radikal-Zwischenstufe auftritt.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19821150619
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis and Circular Dichroism of Both Enantiomers of 2-deuterofluoroacetic acid (= Fluoro[2H1]acetic acid) (1996)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 1021-1025 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sharpless epoxidation of (E)-1-(trimethylsilyl)[1-2H1]oct-1-en-3-o1 (3a) yielded (1S,2S,3S)- and (1R,2R,3R)-1-(trimethylsilyl)-1,2-epoxy[1-2H1]octan-3-ols (4a and 4b, resp.) which were converted in three steps into (S)- and (R)-fluoro[ 2H1]acetic acid (7a and 7b, resp.) in good yields. Their high isotopic and optical purity was established by 1H- and 19F-NMR, mass, and circular-dichroism spectroscopy.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19960790411
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