Viva Origino
Online ISSN : 1346-6933
Print ISSN : 0910-4003
38 巻, 2 号
  • Arvydas Tamulis, Mantas Grigalavicius
    2010 年 38 巻 2 号 p. 4-17
    発行日: 2010年
    公開日: 2022/01/18
    ジャーナル フリー

      Quantum mechanical density functional theory nonlocal gradient electron correlation interactions methods are used for investigations of various self-assembled photoactive fatty acid micelles. The micelle systems studied are based on a photoactive squarine sensitizer, an 8-oxo-guanine electron donor, cytosine, a fatty acid and its precursor (pFA) molecules. The systems include a water environment and consist of some 400 atoms and are up to about 4.5 nm in diameter. The quantum mechanical based electron correlation interactions are the source of the weak hydrogen and Van der Waals chemical bonds that are critical to the behavior of these systems. Polar solvent molecules such as water increase the strength of these bonds and thus play a central role in the self assembly and functioning of the systems studied. The distances between the separated sensitizer, precursor of fatty acid, and water molecules are comparable to Van der Waals and hydrogen bonding radii. As a result, these nonlinear quantum interactions compress the overall molecular system resulting in a smaller gap between the HOMO and LUMO electron energy levels allowing enhanced tunneling of photoexcited electrons from the sensitizer to pFA.

      The most intense excited states of the photoactive fatty acid micelles are partially composed of LUMO+n states located on the fatty acid precursors when the bis(4-diphenylamine-2-phenyl)-squarine molecule is covalently attached to the 8-oxo-guanine. This coupling also promotes electron hopping (tunneling) to the pFA molecules during the most intense absorption excited state. The photoexcited electron tunnels to the waste end of the pFA molecules where it causes these molecules to split due to intense rotation and vibration of the weak chemical bond that joins the waste piece to the fatty acid section of the pFA molecule.

      The most intense absorption lines of the squarine-8-oxo-guanine supermolecule were found to be shifted to the red when these molecules were associated with fatty acid micelles. In addition, the 8-oxo-guanine::cytosine-squarine supramolecule was observed to have an absorption region that covered more of the visible spectrum than a squarine-8-oxo-guanine supermolecule. The redward shift of the intense absorption lines would allow a self reproducing micelle to absorb the light in the longer wavelength region, which may have been important in the environment that life might have developed, in addition to extending the photoactive period into the earlier morning and later evening hours. That allowed better compete for such a kind of evolved photoactive micelles of Fatty Acids World life in getting the food molecules. Furthermore, one notes that the nucleotide caused wavelength shift and broadening of the absorption pattern potentially gives the nucleotides an additional valuable role, other than just a purely genetic one in the early stages of the development of life.

      The main quantum mechanical research result of this paper is that life in the Earth or elsewhere in the Space could have emerged in the form of self-reproducing photoactive fatty acid micelles, which step by step evolved to nucleotide containing micelles due to an enhanced ability to absorb visible light. The nucleotide molecules and their sequences, which in the first period of evolution of fatty acid molecules were useful just for better absorbance of the light in the longer wavelength region, later in the peptide nucleic acid (PNA) or RNA World living organisms took on the role of genetic information storage.

      From the information theory point of view, the nucleotide molecules sequences in the Fatty Acids World micelles carry positional information how to directly provide better relaxation electron transport along the nucleotide-sensitizer chain and in addition providing complimentary copies of that information to the next generation.

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