Process for the purification of DNA on diatomaceous earth

DETAILED DESCRIPTION OF THE INVENTION This invention is directed to a process for the purification of plasmid and other DNA.
both single-stranded and double-stranded, by immobilizing the DNA onto diatomaceous earth particles and eluting the DNA with water or low salt buffer.
The resulting purified DNA is biologically active.
More particularly, the present invention is a process for the purification of plasmid DNA which comprises a) immobilizing the DNA onto diatomaceous earth in the presence of a chaotropic agent: b) washing the resulting diatomaceous earth-bound DNA with an alcohol-containing buffer; c) removing the alcohol-containing buffer; and d) eluting the DNA in a low salt buffer or in water.
In another aspect, the invention is directed generally to the immobilization of DNA onto diatomaceous earth which comprises contacting the DNA with the diatomaceous earth in the presence of a chaotropic agent.
Such immobilized DNA may or may not later be released, depending on the use contemplated, by elution with water or a low salt buffer.
Such immobilization is desirable in that it makes the DNA available for a number of manipulations, treatments or uses.
For example, the DNA may be treated or reacted with a reagent, or it may be used in a diagnostic procedure such as a binding assay.
Diatomaceous earth, also known as kieselguhr or diatomite, is a loosely coherent chalk-like sedimentary rock made up mainly of fragments and shells of hydrous silica secreted by diatoms, microscopic one-celled algae.
The particles are very fine and have high surface area.
Silica content may be as high as 94%.
Because of the intricate structure of the diatom skeletons that form diatomaceous earth, the silica has a very different physical structure from other forms in which it occurs.
Diatomaceous earth is available commercially in three forms: natural, calcinated and flux-calcinated.
Calcinated diatomaceous earth is diatomaceous earth treated by high temperature calcination at about 980.
degree.
C.
Flux-calcinated diatomaceous earth is prepared by the calcination of the natural product in the presence of flux, generally soda ash although sodium chloride may be used