Enzymatic mutation detection. Phosphate ions increase incision efficiency of endonuclease VII at a variety of damage sites in DNA

Sequence variation in genes and genomic DNA: methods for large-scale analysis

The large-scale typing of sequence variation in genes and genomic DNA presents new challenges for which it is not clear that current technologies are sufficiently sensitive, robust, or scalable. This review surveys the current platform technologies: separation-based approaches, which include mass spectrometry; homogeneous assays; and solid-phase/array-based assays. We assess techniques for discovering and typing variation on a large scale, especially that of single-nucleotide polymorphisms. The in-depth focus is the DNA chip/array platform, and some of the published large-scale studies are closely examined. The problem of large-scale amplification is addressed, and emerging technologies for present and future needs are indicated.

Enzymatic mutation detection: enrichment of heteroduplexes from hybrid DNA mixtures by cleavage-deficient GST-tagged endonuclease VII

A method for the enrichment of heteroduplex DNAs from hybrid DNA mixtures by endonuclease VII is reported. The procedure is based on the ability of a GST-fused cleavage-deficient mutant endonuclease VII (EVII-N62D(GST)) to bind to mismatching nucleotides in heteroduplex DNAs identical to the wild-type enzyme. The GST tag was used for stable immobilisation of the protein to Glutathione Sepharose 4B. This enables the material to withstand the repeated rounds of binding steps required for enrichment of heteroduplex molecules from appropriate samples.