Research ArticleASTROBIOLOGY

Membrane alternatives in worlds without oxygen: Creation of an azotosome

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Science Advances  27 Feb 2015:
Vol. 1, no. 1, e1400067
DOI: 10.1126/sciadv.1400067

Figures

Tables

  • Table 2 Error in OPLS-optimized structures.

    Average difference, for each species, between its OPLS structure and the structure obtained via ab initio optimization with Onsager’s self-consistent reaction field (SCRF) model of an implicit solvent.

    SpeciesΔ(bond
    length) (Å)
    Δ(bond
    angle) (°)
    Δ(dihedral)
    (°)
    Propanenitrile0.000.50.0
    Butanenitrile0.010.50.1
    Pentanenitrile0.010.40.1
    Hexanenitrile0.000.60.2
    Aminopropane0.010.70.7
    Aminobutane0.010.60.6
    Aminopentane0.010.60.4
    Aminohexane0.010.50.2
    Hexane0.010.30.0
    Methane0.021.50.0
    HCN0.010.00.0
    Acrylonitrile0.011.20.0
    Acetonitrile0.000.00.0
    Cyanoacetylene0.056.30.0
    Cyanoallene0.089.50.0
    2,4-Pentadiynenitrile0.0675.80.0
  • Table 3 Pairwise binding energies.

    OPLS and ab initio calculations produced similar results.

    SpeciesOPLS
    (kcal/mol)
    DFTvacuum
    (kcal/mol)
    DFTsolvent
    (kcal/mol)
    Propanenitrile−6.4−7.5−6.2
    Methane0.00.00.0
    HCN−4.1−3.0−2.3
    Acrylonitrile−5.6−6.0−4.9
    Acetonitrile−5.9−6.3−5.0
  • Table 4 Flexibility Ka of nitrile and amine azotosomes, and activation energy ΔE to remove a molecule from each azotosome.
    SpeciesKa (J/m2)ΔE (kcal/mol)
    Acrylonitrile0.2617.1
    Acetonitrile0.375.8
    Propanenitrile0.107.6
    Butanenitrile0.136.4
    Pentanenitrile0.558.4
    Hexanenitrile0.266.0
    Aminopropane0.225.2
    Aminobutane0.196.7
    Aminopentane0.287.7
    Aminohexane0.307.7
    Hexane bilayer2.20
  • Table 5 Gibbs free energy of decomposition.

    The net mechanical work required to remove a molecule from the membrane, within 20% uncertainty. These values are concentration-dependent.

    SpeciesΔG (kcal/mol)
    Acrylonitrile7.6
    Acetonitrile17.4
    Propanenitrile6.4
    Butanenitrile7.1
    Pentanenitrile13.4
    Hexanenitrile11.5
    Aminopropane5.9
    Aminobutane6.7
    Aminopentane9.6
    Aminohexane6.2