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Lysis (/ˈlaɪsɪs/LY-sis; fromGreekλῠ́σῐςlýsis 'loosening') is the breaking down of themembrane of acell, often byviral,enzymic, orosmotic (that is, "lytic"/ˈlɪtɪk/LIT-ik) mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called alysate. Inmolecular biology,biochemistry, andcell biology laboratories,cell cultures may be subjected to lysis in the process of purifying their components, as inprotein purification,DNA extraction,RNA extraction, or in purifyingorganelles.
Many species ofbacteria are subject to lysis by the enzymelysozyme, found in animalsaliva,egg white, and othersecretions.[1] Phage lytic enzymes (lysins) produced duringbacteriophage infection are responsible for the ability of these viruses to lyse bacterial cells.[2]Penicillin and relatedβ-lactamantibiotics cause the death of bacteria through enzyme-mediated lysis that occurs after the drug causes the bacterium to form a defectivecell wall.[3] If the cell wall is completely lost and the penicillin was used ongram-positive bacteria, then the bacterium is referred to as aprotoplast, but if penicillin was used ongram-negative bacteria, then it is called aspheroplast.
Cytolysis occurs when a cell bursts due to an osmotic imbalance that has caused excess water to move into the cell.
Cytolysis can be prevented by several different mechanisms, including thecontractile vacuole that exists in someparamecia, which rapidly pump water out of the cell. Cytolysis does not occur under normal conditions in plant cells because plant cells have a strong cell wall that contains the osmotic pressure, orturgor pressure, that would otherwise cause cytolysis to occur.
Oncolysis is the destruction ofneoplastic cells or of atumour.
The term is also used to refer to the reduction of anyswelling.[4]
Plasmolysis is the contraction ofcells within plants due to the loss of water throughosmosis. In ahypertonic environment, the cell membrane peels off thecell wall and thevacuole collapses. These cells will eventually wilt and die unless the flow of water caused by osmosis can stop the contraction of thecell membrane.[5]
Erythrocytes' hemoglobin releasefree radicals in response to pathogens when lysed by them. This can damage the pathogens.[6][7]
Cell lysis is used in laboratories to break open cells and purify or further study their contents. Lysis in the laboratory may be affected byenzymes ordetergents or otherchaotropic agents. Mechanical disruption of cell membranes, as by repeated freezing and thawing,sonication, pressure, orfiltration may also be referred to as lysis. Many laboratory experiments are sensitive to the choice of lysis mechanism; often it is desirable to avoid mechanicalshear forces that would denature or degrade sensitive macromolecules, such asproteins andDNA, and different types of detergents can yield different results. The unprocessed solution immediately after lysis but before any further extraction steps is often referred to as acrude lysate.[8][9]
For example, lysis is used inwestern andSouthern blotting to analyze the composition of specificproteins,lipids, andnucleic acids individually or ascomplexes. Depending on thedetergent used, either all or some membranes are lysed. For example, if only thecell membrane is lysed thengradient centrifugation can be used to collect certainorganelles. Lysis is also used forprotein purification,DNA extraction, andRNA extraction.[8][9]
Several methods for cell lysis exist, sometimes used in combination. Examples include liquid homogenization, freeze thawing, and physical disruption such as sonication, or the use of hypotonic solutions that cause osmotic swelling and eventual bursting of the cell.[10]
This method uses chemical disruption. It is the most popular and simple approach. Chemical lysis chemically deteriorates/solubilizes the proteins and lipids present within the membrane of targeted cells.[11] Common lysis buffers containsodium hydroxide (NaOH) andsodium dodecyl sulfate (SDS). Cell lysis is best done at a pH range of 11.5–12.5. Although simple, it is a slow process, taking anywhere from 6 to 12 hours.[12]
This method uses ultrasonic waves to generate areas of high and low pressure which causes cavitation and in turn, cell lysis. Though this method usually comes out clean, it fails to be cost effective and consistent.[11]
This method uses physical penetration to pierce or cut a cell membrane.[11]
This method uses enzymes such as lysozyme or proteases to disintegrate the cell membrane.[13]