Nucleic acid aptamers stabilize proteins against different types of stress conditions.

It has been observed that the same osmolyte cannot provide protection to a protein exposed to more than one stress condition. We wanted to study the effect of nucleic acid aptamers on the stabilization of proteins against a variety of stress conditions. Adjuvanted tetanus toxoid was exposed to thermal, freeze-thawing, and agitation stress. The stability and antigenicity of the toxoid were measured. Using nucleic acid aptamers selected against tetanus toxoid, we show that these specific RNA sequences were able to stabilize alumina-adsorbed tetanus toxoid against thermal-, agitation-, and freeze-thawing-induced stress. Binding affinity of the aptamer-protein complex did not show any significant change at elevated temperature as compared with that at room temperature, indicating that the aptamer protected the protein by remaining bound to it under stress conditions and did not allow either the protein to unfold or to promote protein-protein interaction. Thus, we show that by changing the stabilization strategy from a solvent-centric to a protein-centric approach, the same molecule can be employed as a stabilizer against more than one stress condition and thus probably reduce the cost of the product during its formulation.