Ag⁺-Mediated Assembly of 5′-Guanosine Monophosphate

Abstract

Polymorphic forms of nucleic acids provide platforms for new nanomaterials, and transition metal cations give access to alternative arrangements of nucleobases by coordinating with electron-rich functional groups. Interaction of Ag+ with 5’-guanosine monophosphate (5’-GMP) is considered in this work. Ag+ promotes nucleotide stacking and aggregation, as indicated by the increased viscosity of 5’-GMP solutions with Ag+, magnification of the circular dichroism response of guanine by Ag+, and exothermic reactions between Ag+ and guanine derivatives. Isothermal titration calorimetry studies show that the reaction is favored starting at 10 μM 5’-GMP. Utilizing the exothermic heat change associated with reaction of Ag+ with 5’-GMP, local structure within the aggregate was assessed. Based on salt dependence and comparison with the corresponding nucleoside, the dianionic phosphate of 5’-GMP is one binding site for Ag+, although this electrostatic interaction is not a dominant contribution to the overall heat change. Another binding site is the N7 on the nucleobase, as determined via studies with 7-deazaguanosine. Besides this binding site, Ag+ also associates with the O6, as earlier studies deduced from the shift in the carbonyl stretching frequency associated with adduct formation. With these two binding sites on the nucleobase, the empirical stoichiometry of ~1 Ag+:nucleobase derived from the calorimetry studies indicates that Ag+ coordinates two nucleobases. The proposed structural model is a Ag+-mediated guanine dimer within a base stacked aggregate.

Ten-Atom Silver Cluster Signaling and Tempering DNA Hybridization

“…Calorimetry studies were conducted using a Microcal VP-ITC (Northhampton, MA) controlled by Origin 7.0 software. 51 Heat changes associated with the titration were determined by integrating the power required to maintain reference and sample cells at the same temperature. Heat changes associated with dilution of AgNO 3 were subtracted after saturation of the binding sites.…”

Self-assembly of guanosine and deoxy-guanosine into hydrogels: monovalent cation guided modulation of gelation, morphology and self-healing properties

“…[12][13][14][15][16][17][18][19][20][21][22][23][24][25] Although metal ion induced guanosine-based G-quadruplex and hydrogel formation has been rst reported in the early 1960s, only a small number of metal ions (Na + , K + and Ag + ) are known to contribute to gel formation with guanosine (or guanosine analogues) via G-quadruplex formation. [25][26][27] However, to the best of our knowledge, metal ion induced hydrogelation of deoxy-guanosine has not been explored yet. Despite this lengthy history, there is a limitation for the potential applications of guanosine gels (Na + and K + induced G gels) because of their poor lifetime stability.…”

Dynamic combinatorial chemistry on a monolayer protected gold nanoparticle

“…8, 9 However, despite the enormous activity in this research area, DCC on nanoparticles has so far remained relatively unexplored with limited examples dedicated to surfactant-based systems. [10][11][12][13] Yet, DCC at surfaces gives an 25 unprecedented opportunity for developing self-selected nanosystems for applications in sensing and (bio)recognition or as responsive materials. 14 In particular the use of gold nanoparticles as scaffold would very appealing, because of their attractive properties related to stability, 30 (bio)compatibility, and intrinsic photophysical properties, which has led to numerous applications in diagnostics and nanomedicine.…”

“…2a). Samples 25 were centrifuged only for a limited time (typically 15 sec) to avoid large changes in the volume of the nanoparticle solution (max 20 %), because large changes in concentration could affect the composition at thermodynamic equilibrium. All measurements were performed in triplicate (see Fig.…”

“…2c+e interaction between Ag + and guanine. 24,25 It is pointed out, though, that the self-selection in our system is determined by the affinity of the formed Ag + -85 Fig. 2 a) Schematic representation of the ultrafiltration experiments.…”