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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 66 (1994), S. 4093-4096 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-072X
    Keywords: Key words     Hyphomicrobium ; Dimethylsulphoxide reductase ; Periplasmic enzymes ; Chemolithoheterotrophic growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract      Hyphomicrobium EG can grow with dimethylsulphoxide as sole carbon and energy source with oxygen as electron acceptor. In the present work we have found that the dimethylsulphoxide reductase of this bacterium could be assayed with dithionite-reduced methylviologen as reductant but not with NADH. Sub-cellular fractionation of Hyphomicrobium EG showed that the dimethylsulphoxide reductase was a periplasmic enzyme. An antibody to the dimethylsulphoxide reductase of Rhodobacter capsulatus cross-reacted with a polypeptide in the periplasmic fraction from Hyphomicrobium EG which had the same M r as the dimethylsulphoxide reductase of Rhodobacter capsulatus. It is suggested that the reduction of dimethylsulphoxide in Hyphomicrobium involves respiratory electron transfer.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-072X
    Keywords: Rhodobacter capsulatus ; Periplasmic enzymes ; Nitrate reductase ; Trimethylamine-N-oxide/dimethylsulphoxide/chlorate reductase ; Molybdenum cofactor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The periplasmic dissimilatory nitrate reductase from Rhodobacter capsulatus N22DNAR+ has been purified. It comprises a single type of polypeptide chain with subunit molecular weight 90,000 and does not contain heme. Chlorate is not an alternative substrate. A molybdenum cofactor, of the pterin type found in both nitrate reductases and molybdoenzymes from various sources, is present in nitrate reductase from R. capsulatus at an approximate stoichiometry of 1 molecule per polypeptide chain. This is the first report of the occurrence of the cofactor in a periplasmic enzyme. Trimethylamine-N-oxide reductase activity was fractionated by ion exchange chromatography of periplasmic proteins. The fractionated material was active towards dimethylsulphoxide, chlorate and methionine sulphoxide, but not nitrate. A catalytic polypeptide of molecular weight 46,000 was identified by staining for trimethylamine-N-oxide reductase activity after polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. The same polypeptide also stained for dimethylsulphoxide reductase activity which indicates that trimethylamine-N-oxide and dimethylsulphoxide share a common reductase.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 194-196 
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Dimethylsulfoxide reductase from the photosynthetic bacterium Rhodobacter capsulatus has been crystallized in two similar forms which are suitable for X-ray structure determination. Both crystals forms belong to space group P4122 or P4322, with cell dimensions a = b = 80.81, c = 229.75 Å (type I crystals) or a = b = 89.30, c = 230.05 Å (type II crystals) and one molecule in the asymmetric unit. Diffraction has been observed to at least 2.0 Å in type I crystals and to 2.6 Å in type II crystals. Dimethylsulfoxide reductase from Rhodobacter is the simplest molybdenum oxotransferase known and this makes it an ideal model to study the structure and function of this class of enzymes.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 23 (1992), S. 0 
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. In southern Africa rainbow trout, Oncorhynchus my kiss (Walbaum), are generally cultured at temperatures between 18 and 22°C, which is higher than the optimal thermal range for maximum growth in this species. Experiments were undertaken on two size classes of fish (〈4·5g and 〉25g) to determine the gross changes in protein and lipid requirements at these temperatures. The optimal protein and lipid requirements of the smaller fish were found to be 40% and 20–30% of the diet respectively. These levels are significantly different to those under optimal thermal conditions. The protein requirements of the larger fish remained at the ‘threshold level’ of 35% of the diet, although lipid requirements rose lo between 20 and 23% of the diet. The results are discussed in terms of the animal's scope for growth.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1327
    Keywords: Key words DMSO reductase ; Molybdenum ; Pterin ; Molybdopterin ; Crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  The 1.82-Å X-ray crystal structure of the oxidised (Mo(VI)) form of the enzyme dimethylsulfoxide reductase (DMSOR) isolated from Rhodobacter capsulatus is presented. The structure has been determined by building a partial model into a multiple isomorphous replacement map and fitting the crystal structure of DMSOR from Rhodobacter sphaeroides to the partial model. The enzyme structure has been refined, at 1.82-Å resolution, to an R factor of 14.8% (R free = 18.4%). The molybdenum is coordinated by seven ligands: four dithiolene sulfurs, Oγ of Ser147 and two oxo groups. The four sulfur ligands, at a metal-sulfur distance of 2.4 Å or 2.5 Å, are contributed by the two molybdopterin guanine dinucleotide (MGD) cofactors. The coordination sphere of the molybdenum is different from that in previously reported structures of DMSOR from R. sphaeroides and R. capsulatus. The 2.8-Å structure of DMSOR, reduced by addition of sodium dithionite, is also described and differs from the structure of the oxidised enzyme by the removal of a single oxo ligand from the molybdenum coordination sphere. A structure, at 2.5-Å resolution, has also been obtained from crystals soaked in mother liquor buffered at pH 7.0. No differences are observed in the structure at pH 7 when compared with the native crystal structure at pH 5.5.
    Type of Medium: Electronic Resource
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  • 7
    Publication Date: 2013-01-19
    Description: Streptococcus pneumoniae (the pneumococcus) is a major human pathogen that is carried asymptomatically in the nasopharynx by up to 70% of the human population. Translocation of the bacteria into internal sites can cause a range of diseases, such as pneumonia, otitis media, meningitis, and bacteremia. This transition from nasopharynx to growth at systemic sites means that the pneumococcus needs to adjust to a variety of environmental conditions, including transition metal ion availability. Although it is an important nutrient, iron potentiates oxidative stress, and it is established that in S. pneumoniae , expression of iron transport systems and proteins that protect against oxidative stress are regulated by an orphan response regulator, RitR. In this study, we investigated the effect of iron and manganese ion availability on the growth of a ritR mutant. Deletion of ritR led to impaired growth of bacteria in high-iron medium, but this phenotype could be suppressed with the addition of manganese. Measurement of metal ion accumulation indicated that manganese prevents iron accumulation. Furthermore, the addition of manganese also led to a reduction in the amount of hydrogen peroxide produced by bacterial cells. Studies of virulence in a murine model of infection indicated that RitR was not essential for pneumococcal survival and suggested that derepression of iron uptake systems may enhance the survival of pneumococci in some niches.
    Print ISSN: 0019-9567
    Electronic ISSN: 1098-5522
    Topics: Medicine
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  • 8
    Publication Date: 2016-01-23
    Description: Methylglyoxal is a dicarbonyl compound that acts as a toxic electrophile in biological systems. Methylglyoxal is produced in certain bacteria as a byproduct of glycolysis through methylglyoxal synthase. Like many bacteria, Group A Streptococcus (GAS), a Gram-positive human pathogen responsible for a wide spectrum of diseases, uses a two-step glyoxalase system to remove methylglyoxal. However, bioinformatic analysis revealed that no homologue of methylglyoxal synthase is present in GAS, suggesting that the role of the glyoxalase system is to detoxify methylglyoxal produced by the host. In this study, we investigated the role of methylglyoxal detoxification in the pathogenesis of GAS. A mutant (5448 gloA) , deficient in glyoxylase I (S-lactoylglutathione lyase), was constructed and tested for susceptibility to methylglyoxal, human neutrophil survival and virulence in a murine model of infection. 5448 gloA was more sensitive to methylglyoxal and was also more susceptible to human neutrophil killing. Inhibition of neutrophil myeloperoxidase rescued the gloA -deficient mutant indicating that this enzyme was required for methylglyoxal production. Furthermore, the 5448 gloA mutant was slower at disseminating into the blood in the murine model. These data suggest that neutrophils produce methylglyoxal as an antimicrobial agent during bacterial infection, and the glyoxalase system is part of the GAS defence against the innate immune system during pathogenesis.
    Print ISSN: 0928-8244
    Topics: Biology , Medicine
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  • 9
    Publication Date: 2016-08-20
    Description: Pathogenic bacteria such as Haemophilus influenzae , a major cause of lower respiratory tract diseases, must cope with a range of electrophiles generated in the host or by endogenous metabolism. Formaldehyde is one such compound that can irreversibly damage proteins and DNA through alkylation and cross-linking and interfere with redox homeostasis. Its detoxification operates under the control of HiNmlR, a protein from the MerR family that lacks a specific sensor region and does not bind metal ions. We demonstrate that HiNmlR is a thiol-dependent transcription factor that modulates H. influenzae response to formaldehyde, with two cysteine residues (Cys54 and Cys71) identified to be important for its response against a formaldehyde challenge. We obtained crystal structures of HiNmlR in both the DNA-free and two DNA-bound forms, which suggest that HiNmlR enhances target gene transcription by twisting of operator DNA sequences in a two-gene operon containing overlapping promoters. Our work provides the first structural insights into the mechanism of action of MerR regulators that lack sensor regions.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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  • 10
    Publication Date: 2015-09-02
    Description: Under conditions of low oxygen availability, Neisseria meningitidis and Neisseria gonorrhoeae are able to respire via a partial denitrification pathway in which nitrite is converted to nitrous oxide. In this process, nitrite reductase (AniA), a copper (Cu)-containing protein converts nitrite to NO, and this product is converted to nitrous oxide by nitric oxide reductase (NorB). NorB also confers protection against toxic NO, and so we devised a conditional lethal screen, using a norB mutant, to identify mutants that were resistant to nitrite-dependent killing. After random-deletion mutagenesis of N. meningitidis , this genetic screen identified a gene encoding a Cu chaperone that is essential for AniA function, AccA. Purified AccA binds one Cu (I) ion and also possesses a second binding site for Cu (II). This novel periplasmic Cu chaperone (AccA) appears to be essential for provision of Cu ions to AniA of pathogenic Neisseria to generate an active nitrite reductase. Apart from the Neisseria genus, AccA is distributed across a wide range of environmental Proteobacteria species.—Jen, F. E.-C., Djoko, K. Y., Bent, S. J., Day, C. J., McEwan, A. G., Jennings, M. P. A genetic screen reveals a periplasmic copper chaperone required for nitrite reductase activity in pathogenic Neisseria .
    Print ISSN: 0892-6638
    Electronic ISSN: 1530-6860
    Topics: Biology
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