Tue. Sep 17th, 2019

Cell Disruption Methods (Chemical)

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Cell Disruption is a process of releasing biological content from a cell or a process of obtaining intracellular fluid via methods that opens up cell wall. An overall goal in cell disruption is to obtain intracellular fluid without disrupting any of its components. Chemical methods involves use of detergents, solvents and enzymes.
Cell Disruption Methods (Chemical Methods)

Cell Disruption is a process of releasing biological content from a cell or a process of obtaining intracellular fluid via methods that opens up cell wall. An overall goal in cell disruption is to obtain intracellular fluid without disrupting any of its components.

It is of two types: Mechanical and Non-mechanical.

Non mechanical methods can be classified into physical and chemical methods. Physical methods includes use of osmotic shock, decompression, thermolysis etc. while chemical methods involves use of detergents, solvents and enzymes.

Chemical methods rely on utilization of chemical substances or enzymes in disruption process. The mechanisms of cell breakage involves destroying the cell wall by enzymes, or by interfering or precipitating cell wall proteins.

 

Cell Lysis by detergents

Detergents

They directly damage the cell wall or membrane which lead to release of intracellular content. Detergents used for disrupting cells can be anionic, cationic and non-ionic.

  • Triton X100 (non-ionic detergent) solubilize membrane proteins.
  • Sodium dodecyl sulfate (SDS), an anionic detergent reorganizes cell membrane by disturbing protein-protein interactions.
  • Ethyl trimethyl ammonium bromide (cationic detergent) is believed to act on cell membrane lipopolysaccharides and phospholipids.

Many proteins will be denatured in lysis process which is a disadvantage of detergents in cell lysis.  They may also disturb subsequent downstream processing steps. Thus additional purification step may be required after cell lysis, which limits their utilization in large scale processes. However, detergents are commonly used for cell lysis in laboratory for example once DNA, RNA or proteins are extracted from cells.

 

Cell disruption by detergents

Solvents

Chemical solvents can be utilized for lysis of cells. Organic solvents like DMSO, toluene, ether, benzene, methanol, surfactants, phenyl ethyl alcohol, EDTA, etc. are used to lyse the cell. These solvents extract lipid components from cell wall which leads to release of intracellular components.

E.g. EDTA is used along with enzymes to rupture gram negative cell wall. It destabilizes the lipopolysaccharide layer that are stabilized by cations like Ca2+, Mg2+, etc. EDTA also acts as a chelating agent which captures metal ions leaving holes in cell wall.

Use of solvents is ideal for disrupting plant and mammalian cells. This method can be used with wide range of production organisms but some proteins can be denatured which limits its use.

By the choice of solvent, it might be possible to select the relished product which can be advantageous.. In addition to solvents, cell lysis can be achieved by hydrolysing the cell wall by alkali compound (pH 10.5-12-5). This method is not generally applied in large scale processes

However, there are some limitations in using chemical solvents for disruption of cell. Chemical costs for neutralization of alkali are high and also, products may not be stable in alkali conditions.

 

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