SILICA-GUANIDINIUMTHIOCYANATE DNA ISOLATION USING CASEIN

摘要

DNA purified by the guanidiniumthiocyanate-silica procedure (Boom et al, J. Clin. Microbiol. 28:495-503, 1990) from some sources (e.g. cerebrospinal fluid and urine) has appeared to contain inhibitors of DNA processing enzymes (Taq DNA polymerase, restriction enzymes and DNA ligase). These inhibitors were, at least in part, introduced by the purification procedure itself. The inhibition of DNA processing enzymes could be relieved by the inclusion of alpha casein into the guanidiniumthiocyanate (GuSCN) containing lysisbuffer. Alpha casein is copurified with DNA by simultaneous binding to the silica particles and is subsequently eluted together with the DNA in the last step of the purification procedure after which it exerts its beneficial effects for DNA processing enzymes.