Portella…Orozco {Angew Chem 54: 10488}

Can A Denaturant Stabilize DNA? Pyridine Reverses DNA Denaturation in Acidic pH. Angew Chem Int Ed Engl. 2015 Sep 1;54(36):10488-91.
At neutral pH the thermal stability of duplex DNA can be decreased by addition of pyridine. In acidic solutions, pyridine acts as DNA renaturant, increasing the melting temperature of the duplex further than a solution of NaCl at the same concentration.