Cations have long been associated with formation of native RNA structure and are commonly thought to stabilize the formation of tertiary contacts by favorably interacting with the electrostatic potential of the RNA, giving rise to an "ion atmosphere". A significant amount of information regarding the thermodynamics of structural transitions in the presence of an ion atmosphere has accumulated and suggests stabilization is dominated by entropic terms. This work provides an analysis of how RNA-cation interactions affect the entropy and enthalpy associated with an RNA tertiary transition. Specifically, temperature-dependent single-molecule fluorescence resonance energy transfer studies have been exploited to determine the free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) of folding for an isolated tetraloop-receptor tertiary interaction as a function of Na(+) concentration. Somewhat unexpectedly, increasing the Na(+) concentration changes the folding enthalpy from a strongly exothermic process [e.g., ΔH° = -26(2) kcal/mol at 180 mM] to a weakly exothermic process [e.g., ΔH° = -4(1) kcal/mol at 630 mM]. As a direct corollary, it is the strong increase in folding entropy [Δ(ΔS°) > 0] that compensates for this loss of exothermicity for the achievement of more favorable folding [Δ(ΔG°) < 0] at higher Na(+) concentrations. In conjunction with corresponding measurements of the thermodynamics of the transition state barrier, these data provide a detailed description of the folding pathway associated with the GAAA tetraloop-receptor interaction as a function of Na(+) concentration. The results support a potentially universal mechanism for monovalent facilitated RNA folding, whereby an increasing monovalent concentration stabilizes tertiary structure by reducing the entropic penalty for folding.
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http://dx.doi.org/10.1021/bi201420a | DOI Listing |
Anal Chem
January 2025
Department of Chemistry, Capital Normal University, Xisanhuan North Road. 105, Beijing 100048, China.
Continuous and reagentless biomolecular detection technologies are bringing an evolutionary influence on disease diagnostics and treatment. Aptamers are attractive as specific recognition probes because they are capable of regeneration without washing. Unfortunately, the affinity and dissociation kinetics of the aptamers developed to date show an inverse relationship, preventing continuous and reagentless detection of protein targets due to their low dissociation rates.
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January 2025
Key Laboratory of Functional Inorganic Material Chemistry (MOE), School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China.
In such an era of information explosion, improving the level of information security is still a challenging task. Self-erasing luminescent hydrogels are becoming ideal candidates for improving the level of information security with simple encryption and decryption methods. Herein, a lanthanide-polyoxometalate-based self-erasing luminescent hydrogel with time-dependent and resilient properties was constructed through a covalent crosslinked network constructed with polyacrylamide and a non-covalent crosslinked network constructed with [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride/NaDyWO, along with doping urease.
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January 2025
İstanbul Technical University Faculty of Chemical-Metallurgical Engineering, Department of Chemical Engineering, İstanbul, Türkiye.
Objectives: This study focuses on both the formulation of bio-based microspheres containing fampridine for the treatment of multiple sclerosis and provides an alternative to the commercially available product (Fampyra 10 mg, Biogen).
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Int J Biol Macromol
January 2025
Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, 21030, Terengganu, Malaysia. Electronic address:
Effective wound healing requires biocompatible and functional wound dressings. This study explores the synergistic potential of gellan gum (GG), known for its exceptional gel-forming abilities, and acacia stingless bee honey (SBH), for its potent antioxidant properties, in developing advanced wound care solutions. GG hydrogel films incorporated with varying concentrations of SBH (v/v) at 10 % (GGSBH10), 15 % (GGSBH15), and 20 % (GGSBH20) were characterized.
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