Entrapment of water by subunit c of ATP synthase

We consider an ancient protein, and water as a smooth surface, and show that the interaction of the two allows the protein to change its hydrogen bonding to encapsulate the water. This property could have made a three-dimensional microenvironment, 3–4 Gyr ago, for the evolution of subsequent complex water-based chemistry. Proteolipid, subunit c of ATP synthase, when presented with a water surface, changes its hydrogen bonding from an α-helix to β-sheet-like configuration and moves away from its previous association with lipid to interact with water surface molecules. Protein sheets with an intra-sheet backbone spacing of 3.7 Å and inter-sheet spacing of 6.0 Å hydrogen bond into long ribbons or continuous surfaces to completely encapsulate a water droplet. The resulting morphology is a spherical vesicle or a hexagonal crystal of water ice, encased by a skin of subunit c. Electron diffraction shows the crystals to be highly ordered and compressed and the protein skin to resemble β-sheets. The protein skin can retain the entrapped water over a temperature rise from 123 to 223 K at 1×10−4 Pa, whereas free water starts to sublime significantly at 153 K

Polymer Amide as an Early Topology

Hydrophobic polymer amide (HPA) could have been one of the first normal density materials to accrete in space. We present ab initio calculations of the energetics of amino acid polymerization via gas phase collisions. The initial hydrogen-bonded di-peptide is sufficiently stable to proceed in many cases via a transition state into a di-peptide with an associated bound water molecule of condensation. The energetics of polymerization are only favorable when the water remains bound. Further polymerization leads to a hydrophobic surface that is phase-separated from, but hydrogen bonded to, a small bulk water complex. The kinetics of the collision and subsequent polymerization are discussed for the low-density conditions of a molecular cloud. This polymer in the gas phase has the properties to make a topology, viz. hydrophobicity allowing phase separation from bulk water, capability to withstand large temperature ranges, versatility of form and charge separation. Its flexible tetrahedral carbon atoms that alternate with more rigid amide groups allow it to deform and reform in hazardous conditions and its density of hydrogen bonds provides adhesion that would support accretion to it of silicon and metal elements to form a stellar dust material

Polymer amide as a source of the cosmic 6.2 micron emission and absorption

Cosmic infrared emission and absorption spectra often carry a well-defined and invariant 6.2 micron band that has been proposed to emanate from very small dust grains that may carry polyaromatic hydrocarbons. Hemoglycin, a well-defined polymer of glycine that also contains iron, has been found in meteorites of the primordial CV3 class and therefore originated in the solar protoplanetary disc. In approximate calculations, the principal amide I infrared absorption band of hemoglycin is at 6.04 microns. Hemoglycin, an antiparallel beta sheet structure with two 11-mer glycine chains, has an exact structural analog in antiparallel poly-L-lysine beta sheets which in the laboratory have an absorption peak at 6.21 microns. This wavelength coincidence, the demonstrated propensity of hemoglycin 4.9nm rods to form accreting lattice structures, and its proven existence in the solar protoplanetary disc strongly suggest that the cosmic 6.2 micron emission and absorption could be from small grains that are hemoglycin lattices or shell-like vesicles carrying internal organic molecules of various types. Calculated hemoglycin ultraviolet absorptions associated with iron in the molecule match the observed ultraviolet extinction feature at nominal 2175 Angstroms.Comment: 8 pages, 4 figure

From revolutionary texts to rebellious readers: What is Leitura Popular da Bíblia and is it really ‘popular’?

Inspired by Paulo’s Freire’s popular education for adults and liberation theology’s ‘option for the poor’, Leitura Popular da Bíblia (LPB) was pioneered among poor urban and rural communities throughout Latin America. It emphasised participatory methodologies, critical thinking and community solutions to problems interpreted as political. Importantly, in its early phase, it accompanied and was inserted into revolutionary political and social movements. This article addresses the methodology of LPB and asks critical questions about the notion of ‘popular’ deployed by some liberation theologies. It problematises the community-based presentation of popular in LPB and asks how LPB can transgress its traditional spaces – favelas, factories, student unions – into newly politicised territories that root emancipatory practices in gender, race and (inter-)religious experiences. The article draws on insights from the experiences of LPB currently used in popular movements in Brazil and Latin America, and considers the wider implications for LPB in light of changing popular experiences and changing practices in revolutionary political and social movements