Procedure details the establishment of an amplification procedure for GC-rich sequences. The DNA fragments of interest are amplified in the presence of either 5% DMSO, 1 M betaine, 2 M betaine, 1 M betaine, and 5% DMSO; 2 M betaine and 5% DMSO; 0.4 M tetramethylene sulfone; or without any of the enhancers.