Communication between noncontacting macromolecules

We present a quantitative experimental demonstration of solvent-mediated communication between noncontacting biopolymers. We show that changes in the activity of a solvent component brought about by a conformational change in one biopolymer can result in changes in the physical properties of a second noncontacting biopolymer present in solution. Specifically, we show that the release of protons on denaturation of a donor polymer tin this case, a four-stranded DNA tetraplex, (DNA) modulates the melting temperature of a noncontacting, acceptor polymer [in this case poly(A)]. In addition to such proton-mediated cross talk, we also demonstrate counterion-mediated cross talk between noncontacting biopolymers, Specifically, we show that counterion association/release on denaturation of native salmon sperm DNA (the donor polymer) can modulate the melting temperature of poly(dA)poly(dT) (the acceptor polymer). Taken together, these two examples demonstrate how poly(A) and poly(dA)poly(dT) can serve as molecular probes that report the pH and free salt concentrations in solution, respectively. Further, we demonstrate how such through-solvent dialogue between biopolymers that do not directly interact can be used to evaluate tin a model-free manner) association/dissociation reactions of solvent components (e,g., protons, sodium cations) with one of the two biopolymers. We propose that such through-solution dialogue is a general property of all biopolymers, As a result, such solvent-mediated cross talk should be considered when assessing reactions of multicomponent systems such as those that exist in essentially all biological processes.