title: Modulation of reactivity in the cavity of liposomes promotes the formation of peptide bonds.
abstract: In living cells, reactions take place in membrane-bound compartments, often in response to changes in the environment. Learning how the reactions are influenced by this compartmentalization will help us gain an optimal understanding of living organisms at the molecular level and, at the same time, will offer vital clues on the behavior of simple compartmentalized systems, such as prebiotic precursors of cells and cell-inspired artificial systems. In this work we show that a reactive building block (an activated amino acid derivative) trapped in the cavity of a liposome is protected against hydrolysis and reacts nearly quantitatively with another building block, which is membrane-permeable and free in solution, to form the dipeptide. By contrast, when the activated amino acid is found outside the liposome, hydrolysis is the prevalent reaction, showing that the cavity of the liposomes promotes the formation of peptide bonds. We attribute this result to the large lipid concentration in small compartments from the point of view of a membrane-impermeable molecule. Based on this result, we show how the outcome of the reaction can be predicted as a function of the size of the compartment. The implications of these results on the behavior of biomolecules in cell compartments, abiogenesis, and the design of artificial cell-inspired systems are considered.
authors.affiliation: Institute of Structural and Molecular Biology and Department of Biological Sciences, School of Science, Birkbeck University of London , Malet Street, London WC1E 7HX, U.K.
authors.forename: Anna
authors.initials: A
authors.lastname: Grochmal
authors.affiliation: Institute of Structural and Molecular Biology and Department of Biological Sciences, School of Science, Birkbeck University of London , Malet Street, London WC1E 7HX, U.K.
authors.forename: Luba
authors.initials: L
authors.lastname: Prout
authors.affiliation: Institute of Structural and Molecular Biology and Department of Biological Sciences, School of Science, Birkbeck University of London , Malet Street, London WC1E 7HX, U.K.
authors.forename: Robert
authors.initials: R
authors.lastname: Makin-Taylor
authors.affiliation: CIRCE Crystal Engineering , 07121 Palma de Mallorca, Spain.|Unitat de Polimorfisme i Calorimetria, CCiT, Universitat de Barcelona , 08028 Barcelona, Spain.
authors.forename: Rafel
authors.initials: R
authors.lastname: Prohens
authors.affiliation: Institute of Structural and Molecular Biology and Department of Biological Sciences, School of Science, Birkbeck University of London , Malet Street, London WC1E 7HX, U.K.
authors.forename: Salvador
authors.initials: S
authors.lastname: Tomas
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D006868:Hydrolysis; D008081:Liposomes / Q000737:chemistry*; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D008081:Liposomes; D010455:Peptides