Figure 2.

Solute effects on meting temperature T_M. The melting temperature T_M of double stranded DNA is shifted by solutes. Compatible solutes like betaine, tetrahydropyrimidines and proline lower T_M. Sodium chloride shows the same shift in opposite direction at concentrations tenfold lower. Dyes interacting with dsDNA like SYBR^®-green also increase T_M at those very low concentrations which are used in realtime applications. The applied standard concentrations are not disclosed by the manufacturer. (Kurz and co-workers, unpublished data for 50% GC-content.).