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  • 1980-1984  (12)
  • 1940-1944
  • Analytical Chemistry and Spectroscopy  (8)
  • Kalanchoë  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Circadian rhythms inKalanchoë: the pathway of14CO2 fixation during prolonged light (1984)
    Springer
    Planta 161 (1984), S. 71-80 
    Details
    ISSN: 1432-2048
    Keywords: Crassulacean acid metabolism ; Carbon dioxide fixation ; Circadian rhythm ; Kalanchoë
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 14CO2 was applied repeatedly at 3- to 6-h intervals toKalanchoë daigremontiana leaves during continuous light of differing irradiances. The circadian rhythm in net CO2 uptake in gasexchange measurements and its disappearance at high irradiances was confirmed by oscillating rates of14CO2 incorporation. At 10–30 W m-2 a markedly circadian oscillation in the14CO2-uptake rate was measured; with increasing energy fluence rate the oscillation levelled off at a constant high uptake rate. The labelling patterns obtained during the 10 min of14CO2 fixation indicated that the rhythm of CO2 exchange is the consequence of a rhythmic behaviour in the C4 pathway of CO2 fixation. During the mininum of14CO2 uptake no C4 products were labelled; however, substantial amounts of label were transferred to C4 products during the peaks of14CO2 uptake. Metabolism of C3 and C4 products was also studied in pulsechase experiments at different points of the circadian cycle. In bright light (100 W m-2), when the14CO2 uptake was constantly high, the transfer of label into C4 products (malic acid) was high in spite of the fact that the malate pool is known to be reduced to a permanently low level under these conditions. This led us to the conclusion that it is not the capacity of the phosphoenolpyruvatecarboxylase-mediated CO2 fixation but rather the storage of malic acid in the vacuole that is disturbed under bright-light conditions when the circadian oscillation levelled off.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00951462
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  • 2
    Electronic Resource
    Electronic Resource
    Circadian rhythms in crassulacean acid metabolism: phase relationships between gas exchange, leaf water relations and malate metabolism in Kalanchoë daigremontiana (1984)
    Springer
    Planta 161 (1984), S. 314-319 
    Details
    ISSN: 1432-2048
    Keywords: Carbon dioxide exchange ; Crassulacean acid metabolism ; Kalanchoë ; Leaf water relations ; Phosphoenolpyruvate carboxylase ; Transpiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gas exchange, leaf water relations, malate content and phosphoenolpyruvate (PEP) carboxylase activity in crude extracts were examined for circadian rhythmicity in the crassulacean acid metabolism plant Kalanchoë daigremontiana. At low irradiance (20 W m-2) the rhythm in CO2 uptake continued for several days with a period length of approx. 22 h, whereas the transpiration rhythm was no longer apparent after 24 h. This shows that the CO2 rhythm in continuous light (LL) is not under stomatal control. Circadian oscillations in malate content were detectable for up to 72 h in LL but were of much reduced amplitude. This was reflected in the changes in leaf water relations, which quickly damped after transfer to LL. The activity of PEP carboxylase assayed immediately after extraction showed a rhythmicity for at least 18 h, but after 36 h, values from different plants were scattered. We suggest that the CO2-uptake rhythm is primarily the result of endogenous changes in the activity of PEP carboxylase, which competes to varying degrees with ribulose-1,5-bisphosphate carboxylase for CO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00398721
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  • 3
    Electronic Resource
    Electronic Resource
    Circadian rhythms in Kalanchoë: effects of irradiance and temperature on gas exchange and carbon metabolism (1984)
    Springer
    Planta 160 (1984), S. 264-271 
    Details
    ISSN: 1432-2048
    Keywords: Circadian rhythm ; Crassulacean acid metabolism ; Kalanchoë
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gas exchange in K. blossfeldiana shows a circadian rhythm in net CO2 uptake and transpiration when measured under low and medium irradiances. The period length varies between 21.4 h at 60 W m-2 and 24.0 h at 10 W m-2. In bright light (≧80 W m-2) or darkness there are no rhythms. High leaf temperatures result in a fast dampening of the CO2-uptake rhythm at moderate irradiances, but low leaf temperatures can not overcome the dampening in bright light. The rhythm in CO2 uptake is accompanied by a less pronounced and more rapidly damped rhythm in transpiration and by oscillations in malate levels with the amplitude being highly reduced. The oscillations in starch content, usually observed to oscillate inversely to the acidification in light-dark cycles, disappear after the first cycle in continuous light. The balance between starch and malate levels depends in continuous light on the irradiance applied. Leaves show high malate and low starch content at low irradiance and high starch and low malate in bright light. During the first 12 h in continuous light replacing the usual dark period, malate synthesis decreases with the increasing irradiance. Up to 50 W m-2 starch content decreases; at higher irradiances it increases above the values usually measured at the end of the light period of the 12:12 h light-dark cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402864
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  • 4
    Electronic Resource
    Electronic Resource
    Crassulacean acid metabolism (CAM) in Kalanchoë daigremontiana: Temperature response of phosphoenolpyruvate (PEP)-carboxylase in relation to allosteric effectors (1981)
    Springer
    Planta 152 (1981), S. 181-188 
    Details
    ISSN: 1432-2048
    Keywords: CO2 dark fixation ; Crassulacean acid metabolism ; Kalanchoë ; PEP-carboxylase ; Temperature (PEP-carboxylase)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Net CO2 dark fixation of Kalanchoë daigremontiana varies with night temperature. We found an optimum of fixation at about 15° C; with increasing night temperature fixation decreased. We studied the temperature dependence of the activity of phosphoenolpyruvate (PEP)-carboxylase, the key enzyme for CO2 dark fixation. We varied the pH, the substrate concentration (PEP), and the L-malate and glucose-6-phosphate (G-6-P) concentration in the assay. Generally, lowering the pH and reducing the amount of substrate resulted in an increase in activation by G-6-P and in an increase in malate inhibition of the enzyme. Furthermore, malate inhibition and G-6-P activation increased with increasing temperature. Activity measurements between 10° C and 45°C at a given concentration of the effectors revealed that the temperature optimum and maximum activities at that optimum varied with the effector applied. Under the influence of 5 mol m-3 L-malate the temperature optimum and maximum activity dropped drastically, especially when the substrate level was low (at 0.5 mol m-3 PEP from 32° C to 20° C). G-6-P raised the temperature optimum and maximum activity when the substrate level was low. If both malate and G-6-P were present, intermediate values were measured. We suggest that changes in metabolite levels in K. daigremontiana leaves can alter the temperature features of PEP-carboxylase so that the observed in vivo CO2 dark fixation can be explained on the basis of PEP-carboxylase activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385142
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  • 5
    Electronic Resource
    Electronic Resource
    Aromatic imine stereochemistry as studied by 13C and 1H NMR of 15N-enriched materials (1980)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 13 (1980), S. 293-298 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of thirteen 15N-enriched N-aryl imines derived from benzaldehydes and acetophenones have been prepared and examined by 13C and 1H NMR. Preferred conformations of the C-arvl and N-aryl rings have been deduced from 13C chemical shifts and 13C-15N couplings. Evidence for steric inhibition of resonance in O-alkylated materials is presented. Relative signs of 1J(CN) and 2J(CCN) have been determined in some compounds. An E: Z interconversion barrier of 21.6 kcal mol-1 has been obtained from 1H NMR coalescence data.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270130416
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  • 6
    Electronic Resource
    Electronic Resource
    Linear and angular annelation effects on the 13C NMR spectra of tricyclic aromatic ketones. 1 - annelated indanones (1981)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 16 (1981), S. 156-159 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbon-13 NMR chemical shifts are reported for nine tricyclic aromatic ketones formally derived from indanone. The influences of remote ring size, as well as linear, angular exo and angular endo ketone orientation are examined. Results are compared with available 1H NMR data. For indanone itself, based on selective 1H decoupling experiments, a recently reported CIDNP derived 13C signal assignment is shown to be in error.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270160219
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  • 7
    Electronic Resource
    Electronic Resource
    A carbon-13 nuclear magnetic resonance spectral investigation of substituted triphenyl phosphates (1982)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 19 (1982), S. 98-101 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C NMR chemical shifts and 13C—31P couplings are reported for triphenyl phosphate and 13 alkyl derivatives. In ortho-alkylated materials, it is found that the upfield γ shielding effect is only operative when the carbon atom, situated γ to the exocyclic oxygen, bears at least one hydrogen. Conformational changes about the aryl—O bond can be monitored via the vicinal 31p—O—C—13C couplings.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270190211
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  • 8
    Electronic Resource
    Electronic Resource
    Rule-based mass spectrum prediction and ranking: Applications to structure elucidation of novel marine sterolsSee Ref. 1. (1980)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1980), S. 355-366 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel, computer aided approach to the interpretation of mass spectra is documented by its application to a series of recently isolated marine sterols. The method consists of construction of biosynthetically plausible candidate structures, prediction of their major mass spectral fragmentation paths using class-specific rules derived from a training set of known compounds, and a system of ranking candidate structures based on a comparison of the predicted and observed spectra.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210150709
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  • 9
    Electronic Resource
    Electronic Resource
    Electronic and steric effects in arylphosphoramidates and phosphorimidates as monitored by carbon-13 nuclear magnetic resonance (1980)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 14 (1980), S. 517-521 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C NMR chemical shifts and 13C—31P couplings are reported for ten arylphosphoramidates and five arylphoshorimidates. The para-carbon chemical shifts in the phosphoramidates are interpreted in terms of substantial nitrogen lone pair delocalization into the aromatic ring, a phenomenon which is subject to steric inhibition of resonance. By contrast, in the phosphorimidates the electron release into the phenyl ring is not attenuated by steric congestion. Conformational changes about the aryl—N bond in all compounds have been monitored by vicinal 31P—N—C—13C couplings.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270140618
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  • 10
    Electronic Resource
    Electronic Resource
    Differentiation of polycyclic aromatic hydrocarbons using electron capture negative chemical ionizationResearch sponsored by the Office of Health and Environmental Research, US Department of Energy under contract W-7405-eng-26 with the Union Carbide Corporation. (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 19 (1984), S. 486-489 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of isomeric polycyclic aromatic hydrocarbons may be distinguished using electron capture negative chemical ionization when methane is used as a buffer gas, including benzo[a]pyrene and benzo[e]pyrene. The ionization behavior of these compounds may be predicted, on the basis of their electron afinities, allowing compounds to be distinguished without the use of standards.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210191005
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