Life Technologies Inc. markets the FTA Gene Guard System for convenient collection, transport, and room temperature storage of blood and subsequent DNA preparation for PCR, RFLP analysis, and genomics. This system prepares PCR-ready DNA in less than an hour and is available in card and microwell plate formats. Plants Purifying DNA from plants can be difficult because of the polyphenolic compounds and polysaccharides in plant leaves. Polysaccharides, phenolic compounds, and other contaminants remain in the supernatant under these conditions and can be washed away. Precipitated DNA is solubilized by raising the salt concentration and concentrated by an ethanol or isopropanol precipitation.
Several companies make genomic DNA preparation kits specifically for use with plant material.
Some standard genomic DNA purification kits also efficiently isolate genomic DNA from plant material. The bacterial cell wall must be scaled when purifying genomic DNA from bacteria. The main component of bacterial cell walls is peptidoglycan, which is made up of a backbone of repeating disaccharides. Each disaccharide is joined to a tetrapeptide of alternating L and D amino acids, and peptide bridges linking the C terminus of one tetrapeptide to the NH 2 group of a tetrapeptide on a neighboring glycan chain. Polysaccharide and residual proteins are removed by CTAB precipitation and nucleic acids recovered by isopropanol precipitation.