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  • AERODYNAMICS  (9)
  • Analytical Chemistry and Spectroscopy  (5)
  • Humans  (4)
  • Escherichia coli  (3)
  • 1985-1989  (21)
  • 1935-1939
  • 1
    ISSN: 1432-072X
    Keywords: Iron-limitation ; Escherichia coli ; Respiratory chains ; Cytochromes ; Gallium ; Metal uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of iron limitation on growth, the composition and function of the respiratory chains, and gallium uptake inEscherichia coli have been studied. Decreasing the iron concentration in a defined medium using Chelex resin gave lower growth yields in both continuous culture and prolonged batch culture. In the former, ironlimited (entering [Fe]≤2.0 μM) cells exhibited diminished respiration rates, respiration-driven proton translocation quotients, and levels of non-haem iron and cytochromes. The cellular concentration of haemoproteinb-590 (a cytochromea 1-like hydroperoxidase) decreased 20-fold on iron limitation, whilst a CO-binding pigment with an absorption maximum in the dithionite-treated form near 500 nm appeared. Gallium(III) (9 μM) added to iron-limited, but not iron-sufficient, cultures diminished growth yields further; cells grown with low entering concentrations of iron took up less gallium than iron-sufficient cells. These results are attributed to the interference by gallium(III) with siderophore-mediated metal uptake. Gallium also stimulated iron uptake and was itself accumulated by iron-sufficient cells, suggesting that gallium(III) also affects the iron transport system(s) of low affinity.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-072X
    Keywords: Copper-limitation ; Escherichia coli ; Cytochrome oxidases ; Oxygen reduction ; Respiratory chains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role(s) of copper in a bacterial cytochrome oxidase of the aa 3-type was investigated by growth of Paracoccus denitrificans NCIB 8944, in batch and steady state continuous culture, in a medium from which the bulk of the copper had been extracted. In a medium containing approximately 0.02 μM copper, cellular copper content, cytochromes a+a 3 and cytochrome a 3 were reduced to 55%, 58% and 33% respectively of control values and there were also less marked decreases in cytochromes c+c 1 (to 85%) and a CO-binding b-type cytochrome, possibly cytochrome o (to 71%). Copper deficiency elicited in reduced minus oxidized difference spectra a shift to shorter wavelengths and narrowing of the band width of the α-band of the oxidase, and loss of a (negative) band near 830 nm attributable to CuA (the copper functionally associated with haem a in the oxidase complex). The oxidase in copper-deficient cells reacted with oxygen to form the oxy “Compound A” at rates similar to that in control cells but CO recombination to ferrous haem a 3 was slowed 4-fold in the copper deficient case. The results are interpreted as indicating loss of CuA and changes in the proportions of haems a and a 3 with retention of catalytic activity. Titrations of respiration rates with antimycin suggested that copper deficiency did not result in diversion of electron flux through an antimycin A-insensitive, cytochrome o-terminated branch of the respiratory chain.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 213 (1988), S. 99-104 
    ISSN: 1617-4623
    Keywords: Promoters ; Escherichia coli ; Proteus vulgaris ; Hemolysin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The hemolytic activity of Escherichia coli and Proteus vulgaris is determined by common contiguous genes encoding synthesis (hly C, hly A) and specific secretion (hly B, hly D) of active hemolysin. Nevertheless, the hlyC-proximal DNA sequences directing production of the homologous hemolysins by the recombinant DNAs P. vulgaris pVU763-709 and E. coli pANN202-312 showed no extensive homology. Primer extension and S1 nuclease protection were used to define in the two sequences the 5′ termini of hly transcripts synthesized in vivo and thus to infer the active hly promoters sequences. The E. coli hly C upstream region contained three separate promotors directing in vivo hly transcription, while the corresponding transcription of the P. vulgaris hly operon originated from a single distinct promotor, the-35 and-10 sequences of which formed part of an inverted repeat sequence. Elevated hemolytic activity caused by upstream Tn5 insertions in pVU763-709 resulted from increased transcription from this promotor.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 615-621 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The collisionally activated decomposition of [M + H]+ ions, generated by fast atom bombardment (FAB) of glutathione conjugates, has been studied by tandem mass spectrometry (MS/MS) using hybrid sector/quadrupole instruments. Abundant fragments of diagnostic utility were present in the daughter ion spectra. Common fragmentation modes were observed but their relative importance was strongly dependent on the nature of the conjugated species. As an example of a general approach to the characterization of glutathione conjugates in biological samples, the acetaminophen-glutathione conjugate was identified in rat bile, following coadministration of (2H0)- and (2H3)acetaminophen, using the experimental sequence: (i) conventional FAB mass spectrometric analysis, (ii) MS/MS using constant neutral loss (129 u) scanning to identify parent ions corresponding to glutathione conjugates, (iii) MS/MS to yield daughter ion spectra of parents so identified and corresponding to (2H0)- and (2H3)-labeled conjugates.
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 16 (1988), S. 409-413 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas chromatography/electron capture negative ion mass spectrometry of eicosanoids, as pentafluorobenzyl (PFB) ester, methyl oxime (where applicable), trimethylsilyl (TMS) ether derivatives, is reported using a double-focusing instrument of trisector configuration. Sub-picogram detection limits were observed for prostaglandins E1, E2 and F2α during selected ion monitoring (SIM) of [M — PFB]- ions. Selected reaction monitoring (SRM) of [M — PFB]- → [M — PFB — TMSOH]-, occurring in the first field-free region, was of modest sensitivity, reflecting the stability of the [M - PFB]- ions. The leukotriene B4 (LTB4) derivative was successfully analyzed by SIM at the low-picogram level. In this instance, the fragmentation [M — PFB]- →[M — PFB — TMSOH] occurred in high yield in the first field-free region. The advantageous improvement in selectivity of detection that may be achieved with SRM was evident during the analysis of a serum extract for LTB4.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 26 (1988), S. 214-223 
    ISSN: 0749-1581
    Keywords: RELAY 2D NMR ; 1H NMR ; 2D NMR Steroids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Relayed coherence transfer (RELAY) two-dimensional NMR spectroscopy was demonstrated to be an effective technique for overcoming the problem of overlapping multiplets in the analysis of the 1H NMR spectra of steroids. Cross-sections through appropriate proton resonances resulted in resolved spectra of the spin systems for each of the saturated rings of the estrogenic hormones 17β- and 17α-estradiol. During RELAY experiments with a fixed delay time of 0.042 s it was possible to observe RELAY cross-peaks between H-11α and 18-CH3 which resulted from magnetization transfer via long-range coupling between 18-CH3 and H-12α. The difference in stereochemistry at C-17 of these estradiol epimers allowed an examination of the effect of substituent configuration on the RELAY cross-peak intensity in order to determine the ability of the RELAY method to provide qualitative structural information.
    Additional Material: 7 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 26 (1988), S. 1058-1061 
    ISSN: 0749-1581
    Keywords: Two-dimensional NMR ; Artifacts ; BIRD pulses ; Coherence transfer ; Methylene groups ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When the proton-proton decoupled heteronuclear two-dimensional chemical shift correlation experiment is applied to a molecule containing methylene groups, the spectra show not only the expected signals at the two proton chemical shifts, but also a strong artifact. This artifact appears at the average of the two proton chemical shifts, and arises from coherence transfer between the two protons caused by the BIRD pulse. It is not caused by strong coupling between the protons, and so may appear in any spectrum. The dependence of this artifact on experimental conditions was analysed, and is illustrated with results obtained on the methylene groups from the cyclophane ring in N6′,N9-octamethylenepurinecyclophane.
    Additional Material: 3 Ill.
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  • 8
    ISSN: 0749-1581
    Keywords: 1H ; 13C NMR 2D NMR ; C-Glycopyranosides ; C-Glycofuranosides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: C-Glycopyranosides and C-glycofuranosides were identified using 13C and 1H chemical shift and coupling constant data. Full assignments for all α- and β-anomers were made possible by recourse to carbon-proton chemical shift correlation spectroscopy. Greater steric shielding effects were observed on the carbon atoms in cis-1,2-substituted compounds compared with their trans counterparts. Consistent proton chemical shift differences were also noted in that the anomeric protons resonate at lower field in all cis-1,2-isomers.
    Additional Material: 2 Ill.
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  • 9
    Publication Date: 1989-11-03
    Description: A complementary DNA (cDNA) for ubiquitin carboxyl-terminal hydrolase isozyme L3 was cloned from human B cells. The cDNA encodes a protein of 230 amino acids with a molecular mass of 26.182 daltons. The human protein is very similar to the bovine homolog, with only three amino acids differing in over 100 residues compared. The amino acid sequence deduced from the cDNA was 54% identical to that of the neuron-specific protein PGP 9.5. Purification of bovine PGP 9.5 confirmed that it is also a ubiquitin carboxyl-terminal hydrolase. These results suggest that a family of such related proteins exists and that their expression is tissue-specific.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wilkinson, K D -- Lee, K M -- Deshpande, S -- Duerksen-Hughes, P -- Boss, J M -- Pohl, J -- New York, N.Y. -- Science. 1989 Nov 3;246(4930):670-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2530630" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; B-Lymphocytes/enzymology ; Base Sequence ; Cattle ; DNA/genetics ; Humans ; Isoenzymes/genetics ; Molecular Sequence Data ; Neuropeptides/*genetics/isolation & purification ; Sequence Homology, Nucleic Acid ; Thiolester Hydrolases/*genetics/isolation & purification ; Ubiquitin Thiolesterase
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 10
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1986-01-31
    Description: Contrary to the orthodox view that optical image quality should "match" the photoreceptor grain, anatomical data from the eyes of various animals suggest that the image quality is significantly superior to the potential resolution of the cone mosaic in most retinal regions. A new theory is presented to explain the existence of this relation and to better appreciate eye design. It predicts that photoreceptors are potentially visible through the natural optics.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Snyder, A W -- Bossomaier, T R -- Hughes, A -- New York, N.Y. -- Science. 1986 Jan 31;231(4737):499-501.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3941914" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cats ; Humans ; Models, Neurological ; Photoreceptor Cells/*anatomy & histology ; Rats ; Snakes ; Species Specificity ; *Vision, Ocular ; *Visual Perception
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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