Purification of cloned and genomic DNA by guanidine thiocyanate/isobutyl alcohol fractionation.

We have developed a rapid and efficient method to purify cloned or high molecular weight eukaryotic DNA from cell lysates using guanidine thiocyanate and isobutyl alcohol. This simple two-step extraction procedure utilizes isobutyl alcohol to fractionate DNA away from cell lysates containing guanidine thiocyanate, yielding a relatively large quantity of pure DNA. The yield of DNA is approximately twice that obtained by the organic extraction method. DNA purified with this chaotropic-based protocol is suitable for a variety of applications including restriction analysis, double-stranded sequencing, PCR, subcloning, and transcription.