title: Hammerhead ribozyme activity and oligonucleotide duplex stability in mixed solutions of water and organic compounds.
abstract: Nucleic acids are useful for biomedical targeting and sensing applications in which the molecular environment is different from that of a dilute aqueous solution. In this study, the influence of various types of mixed solutions of water and water-soluble organic compounds on RNA was investigated by measuring the catalytic activity of the hammerhead ribozyme and the thermodynamic stability of an oligonucleotide duplex. The compounds with a net neutral charge, such as poly(ethylene glycol), small primary alcohols, amide compounds, and aprotic solvent molecules, added at high concentrations changed the ribozyme-catalyzed RNA cleavage rate, with the magnitude of the effect dependent on the NaCl concentration. These compounds also changed the thermodynamic stability of RNA base pairs of an oligonucleotide duplex and its dependence on the NaCl concentration. Specific interactions with RNA molecules and reduced water activity could account for the inhibiting effects on the ribozyme catalysis and destabilizing effects on the duplex stability. The salt concentration dependence data correlated with the dielectric constant, but not with water activity, viscosity, and the size of organic compounds. This observation suggests the significance of the dielectric constant effects on the RNA reactions under molecular crowding conditions created by organic compounds.
authors.affiliation: Department of Nanobiochemistry, Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe, Japan.
authors.forename: Shu-Ichi
authors.initials: S
authors.lastname: Nakano
authors.affiliation: Department of Nanobiochemistry, Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe, Japan ; Department of Chemistry, Faculty of Science and Engineering, Konan University, Kobe, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kitagawa
authors.affiliation: Department of Nanobiochemistry, Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Miyoshi
authors.affiliation: Department of Nanobiochemistry, Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe, Japan ; Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, Kobe, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Sugimoto
keywords: Dielectric constant; Enzyme; Molecular crowding; RNA; Thermal stability