RNA extraction is the purification of
RNA
Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...
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 th ...
enzymes in cells and tissues, which can rapidly degrade RNA. Several methods are used in
molecular biology
Molecular biology is a branch of biology that seeks to understand the molecule, molecular basis of biological activity in and between Cell (biology), cells, including biomolecule, biomolecular synthesis, modification, mechanisms, and interactio ...
to isolate RNA from samples, the most common of these is
guanidinium thiocyanate-phenol-chloroform extraction. Usually, the phenol-chloroform solution used for RNA extraction has lower pH, this aids in separating DNA from RNA and leads to a more pure RNA preparation. 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 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. This includes solutions that are used for RNA extraction, which can be treated with chemicals such as DEPC. For the same reason, experimenters take special care not to let their bare skin touch the equipment, to avoid contaminating the sample with RNAses that are present on human skin. Broad RNAse inhibitors are also commercially available and sometimes added to in vitro transcription (RNA synthesis) reactions.
[https://www.neb.com/en-us/products/m0314-rnase-inhibitor-murine?srsltid=AfmBOorRgG1NYgy4ThzkW6LbtJwCHqLPjtjeCLTj_sG9qN74lyRHyVpO]
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. DNA extraction is the process of isolating DNA from the cells of an organism isolated from a sample, typically a biological sample such as blood, saliva, ...
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Ethanol precipitation
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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