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  • 1
    Publication Date: 2011-08-24
    Description: Attempts to solve two fundamental questions are described: the first concerns which mechanisms were responsible for the self-assembly of membrane structures on the prebiotic Earth, and the second concerns the routes by which considerable amounts of membrane amphiphiles formed from simpler hydrocarbons. The physicochemical properties of several amphiphilic compounds extracted from the Murchison carbonaceous chondrite were studied, using infra-red and fluorescent spectroscopy, measurements of surface activity, chromato-mass spectrometry, and polarization and electron microscopy. The results supported previous observations that amphiphilic and aromatic hydrocarbons were present in significant quantities, and the first demonstration of surface activity among a number of acidic derivatives of hydrocarbons is reported. In addition, one fraction of the surface-active compounds can form bilayer structures, showing that membranes could have self-assembled on the prebiotic Earth. Photochemical oxidation of hydrocarbons is shown to be a likely source of the amphiphilic molecules required for the self-assembly of primary membrane structures.
    Keywords: Exobiology
    Type: Journal of evolutionary biochemistry and physiology (ISSN 0022-0930); Volume 27; 3; 212-7
    Format: text
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  • 2
    ISSN: 1573-9171
    Keywords: solid hydrogen cyanide ; photolysis ; radiolysis ; free radicals ; ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The photolysis of solid hydrogen cyanide and the effects of UV light on60Co-γ-irradiated HCN at 77 K were studied using an ESR technique. As in the case of radiolysis, the HZ2C=N radical formed due to “sticking” of the H atom to the triple bond of the HCN molecule is the main radical product of low-temperature HCN photolysis. The C=N− radicals are accumulated at 77 K in insignificant amounts (≈3 %). It was established that radical and ionic products stabilized in y-irradiated HCN possess photochromism and under the action of UV light enter photochemical reactions leading to their decomposition. Upon photobleaching, the concentration of H2C=N− radicals first increases two- to threefold because of the decomposition of H2C=N− ions and then decreases. The presence of radicals and ions formed upon the low-temperature radiolysis of HCN broadens the optical absorption band of the system, and the boundary of the action spectrum shifts from 280 nm (for nonirradiated HCN) to the visible region at 400–440 nm.
    Type of Medium: Electronic Resource
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