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  • Circularly  (1)
  • Parity nonconservation in weak interactions  (1)
  • 1
    Electronic Resource
    Electronic Resource
    The asymmetry of life (1978)
    Springer
    Journal of molecular evolution 11 (1978), S. 313-332 
    Details
    ISSN: 1432-1432
    Keywords: Evolution ; Optical activity ; Photolysis ; Circularly ; polarized radiation ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Stereoselective physical phenomena and their possible importance for the prevalence of D-sugars and L-aminoacids in living matter are reviewed. A classification is presented according to which a selective force provides a microscopic or macroscopic selection depending on its generality when taken over a macrosystem (a ‘unitary biosphere’ such as the Earth). The microscopic ‘selections’ are not genuine selections because the final sense of asymmetry is here determined by chance, in other words the initial choice is ‘random’, while it is ‘directed’ in the macroscopic selection. Two macroscopic selections appear possible: 1. selection due to an intrinsic energy difference between enantiomorph configurations, 2. selection accomplished by elliptically polarised radiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01733840
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  • 2
    Electronic Resource
    Electronic Resource
    Stereoselective decarboxylation of amino acids in the solid state, with special reference to chiral discrimination in prebiotic evolution (1985)
    Springer
    Journal of molecular evolution 21 (1985), S. 364-370 
    Details
    ISSN: 1432-1432
    Keywords: Chiral selection in chemical systems ; Parity nonconservation in weak interactions ; Origin of prebiotic asymmetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The decarboxylations of sublimated solidd- andl-leucine by nonpolarized γ-rays give quite different quantum yields, indicating significant selection. The G(CO2) value for thed-isomer is higher than that for thel-isomer by a factor of 2 within a dose range of 103–105 rads. The G value for thedl-racemate is close to that of thed-isomer. The effect vanishes if instead of sublimation, crystallization from aqueous solution is the last preparation step. Our results on sublimated leucine agree well with those reported for γ-induced decarboxylation of solid β-phenylalanine prepared similarly by sublimation. The asymmetry increases with longer cooling periods after irradiation. An intrinsic energy difference due to parity nonconservation between enantiomers is discussed as a possible stereoselective mechanism, with special reference to the prebiotic origin of asymmetry in living matter. Other possible sources of the observed effects are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02115656
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