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  • 1
    Electronic Resource
    Electronic Resource
    Two mechanisms of recovery from photoinhibition in vivo: Reactivation of photosystem II related and unrelated to D1-protein turnover (1994)
    Springer
    Planta 194 (1994), S. 15-21 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll fluorescence ; D1 protein ; Photoinhibition (photosynthesis) ; Photosystem II (recovery) ; Spinacia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recovery (at 20° C) of spinach (Spinacia oleracea L.) leaf sections from photoinhibition of photosynthesis was monitored by means of the fluorescence parameter FV/FM of intact leaf tissue and of PSII-driven electron-transport activity of isolated thylakoids. Different degrees of photoinactivation of PSII were obtained by preillumination in ambient air (at 4 or 20° C), CO2-free air or at low and high O2 levels (2 or 41 %) in N2. The kinetics of recovery exhibited two distinct phases. The first phase usually was completed within about 20-60 min and was most pronounced after preillumination in low O2. The slow phase proceeded for several hours leading to almost complete reactivation of PSII. Preincubation of the leaves with streptomycin (SM), which inhibits chloroplast-encoded protein synthesis, inhibited the slow recovery phase only, indicating the dependence of this phase on resynthesis of the reaction-centre protein, D1. The fast recovery phase remained largely unaffected by SM. Both phases were strongly but not totally dependent on irradiation of the leaf with low light. When SM was absent, net degradation of the D1 protein could neither be detected upon photoinhibitory irradiation nor during following incubation of the leaf sections in low light or darkness. In the presence of SM, net D1 degradation was seen and tended to increase with O2 concentration during photoinhibition treatment. Based on these data, we suggest that photoinactivation of PSII in vivo occurs in at least two steps. From the first step, reactivation appears possible in low light without D1 turnover (fast recovery phase). Action of oxygen then may lead to a second step, in which the D1 protein is affected and reactivation requires its removal and replacement (slow phase).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201029
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  • 2
    Electronic Resource
    Electronic Resource
    Unusual amino acids I: Asymmetric synthesis of furylalanine derivatives (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 110-115 
    Details
    ISSN: 0899-0042
    Keywords: furyldehydroamino acid ; enantioselectivity ; hydrogenation ; chiral rhodium complexes ; amino-phosphine-phosphinite ; ligands enantiomers ; (R)- and (S)-isomers ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nonproteinogenic amino acids are valuable active compounds from their pharmacological and biochemical effects and also as novel building blocks for peptides. The preparation of furylalanine derivatives by asymmetric hydrogenation is described. Amino-phosphine-phosphinite-rhodium complexes catalyzed the hydrogenation of the prochiral dehydroamino acid precursors in high rate and with enantioselectivities of 70 - 90% ee. Substrate-catalyst ratios up to 2,000 can be used depending on the catalyst applied. The procedure turns out to be suitable for larger scale preparations.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040208
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  • 3
    Electronic Resource
    Electronic Resource
    (1S,2S)-2-Amino-1-aryl-propane-1,3-diols as convenient educts for the Synthesis of Homochiral (S,S)-Norpseudoephedrine (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 307-312 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A convenient high yield synthesis of homochiral norpseudoephedrine starting from waste products of the chloramphenicol synthesis is described as an example of its utilization in chemical transformations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320305
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  • 4
    Electronic Resource
    Electronic Resource
    Short synthesis of (±)-4,8-dimethyl-1-oxaspiro[4.5]deca-3,7-dien-2-one (andirolactone) using the propynoate/cuprate method (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 603-604 
    Details
    ISSN: 0170-2041
    Keywords: Spirolactone synthesis ; Propynoate, methyl; lithiation ; Organocuprate addition ; Cedrus libanotica ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Racemic 4,8-dimethyl-1-oxaspiro[4.5]deca-3,7-dien-2-one (andirolactone) (1) was synthesized in two steps with 58% overall yield, starting from 4-methyl-3-cyclohexenone (2) and methyl propynoate (3).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1990199001111
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of (±)-Sterpurene and Hydroxylated Derivatives by 1,6-Addition of Organocuprates to Acceptor-substituted Enynes (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 521-525 
    Details
    ISSN: 0170-2041
    Keywords: Stereum purpureum ; Cuprates, organo- ; 1,6-Addition ; Vinylallenes ; Diels-Alder reaction, intramolecular ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of (±)-sterpurene (1), 14-/15-hydroxysterpurene (13), and 11,14-/11,15-dihydroxysterpurene (14) is described. Key steps are the 1,6-addition of lithium dimethylcuprate to the 2-en-4-ynoate 11 and the regioselective trapping of the allenyl enolate with methyl triflate. The vinylallene 6 thus obtained undergoes an intramolecular Diels-Alder reaction to give the tricyclic ester 5, which serves as a common precursor of 1, 13, and 14.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199319930186
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