RNA extraction is the purification of
RNA
Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...
from biological samples. This procedure is complicated by the ubiquitous presence of
ribonuclease
Ribonuclease (commonly abbreviated RNase) is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonucleases can be divided into endoribonucleases and exoribonucleases, and comprise several sub-classes within the ...
enzymes in cells and tissues, which can rapidly degrade RNA. Several methods are used in
molecular biology
Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physi ...
to isolate RNA from samples, the most common of these is
guanidinium thiocyanate-phenol-chloroform extraction
Acid guanidinium thiocyanate-phenol-chloroform extraction (abbreviated AGPC) is a liquid–liquid extraction technique in biochemistry. It is widely used in molecular biology for isolating RNA (as well as DNA and protein in some cases). This metho ...
. The filter paper based lysis and elution method features high throughput capacity.
RNA extraction in liquid nitrogen, commonly using a mortar and pestle (or specialized steel devices known as tissue pulverizers) is also useful in preventing ribonuclease activity.
RNase contamination
The extraction of RNA in molecular biology experiments is greatly complicated by the presence of ubiquitous and hardy RNases that degrade RNA samples. Certain RNases can be extremely hardy and inactivating them is difficult compared to neutralizing
DNase Deoxyribonuclease (DNase, for short) refers to a group of glycoprotein endonucleases which are enzymes that catalyze the hydrolytic cleavage of phosphodiester linkages in the DNA backbone, thus degrading DNA. The role of the DNase enzyme in cells ...
s. In addition to the cellular RNases that are released there are several RNases that are present in the environment. RNases have evolved to have many extracellular functions in various organisms. For example, RNase 7, a member of the
RNase A
Pancreatic ribonuclease family (, ''RNase'', ''RNase I'', ''RNase A'', ''pancreatic RNase'', ''ribonuclease I'', ''endoribonuclease I'', ''ribonucleic phosphatase'', ''alkaline ribonuclease'', ''ribonuclease'', ''gene S glycoproteins'', ''Ceratit ...
superfamily, is secreted by human skin and serves as a potent antipathogen defence. For these secreted RNases, enzymatic activity may not even be necessary for the RNase's
exapted function. For example, immune RNases act by destabilizing the cell membranes of bacteria.
To counter this, equipment used for RNA extraction is usually cleaned thoroughly, kept separate from common lab equipment and treated with various harsh chemicals that destroy RNases. For the same reason, experimenters take special care not to let their bare skin touch the equipment.
See also
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Column purification
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DNA extraction
The first isolation of deoxyribonucleic acid (DNA) was done in 1869 by Friedrich Miescher. Currently, it is a routine procedure in molecular biology or forensic analyses. For the chemical method, many different kits are used for extraction, and s ...
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Ethanol precipitation Ethanol precipitation is a method used to purify and/or concentrate RNA, DNA, and polysaccharides such as pectin and xyloglucan from aqueous solutions by adding ethanol as an antisolvent.
DNA precipitation Theory
DNA is polar due to its highl ...
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Phenol-chloroform extraction
References
External linksTwo-phase wash to solve the ubiquitous contaminant-carryover problem in commercial nucleic-acid extraction kits
by Erik Jue, Daan Witters & Rustem F. Ismagilov; Nature, Scientific reports, 2020.
{{Molecular Biology
Biochemical separation processes
Genetics techniques