Yirong Mo shows that the GC pair has a binding energy (-25.4kcal/mol) that is twice the binding energy of the adenine (A) and thymine (T) pair (-12.4 kcal/mol). This is why these different DNA molecules respond differently toward chemical denaturation in the presence of urea or pyridine and why a higher denaturant concentration is needed to melt DNA with higher GC content. According to Eqs.37, 38, 39,40, an increase in V f of denaturants leads to an increase in the denaturing power of the solution needed to achieve 50% of DNA denaturation.