Detection of punctual mutations

[Carolina Garcia Imhof]

I am wandering if someone could help me to find alternative methods to 
find a punctual mutation in a specific DNA sequence. I know that with 
DGGE I can detect punctual mutations, based on differences of migration 
in the denaturing gel, using G-C clamps. The problem is that those 
differences are between mutations of G instead of A or T, but I do not 
know how to detect a difference if the mutation is of an A instead of T, 
or a G instead of C, or viceversa, because the rate of denaturation would 
not change, and there would not be differnces in migration. If someone could 
help me, please send your 
suggestion to the newsgroup or to caro-gar at uniandes.edu.co. Thank you.