Thermolabile refers to a substance which is subject to destruction,
decomposition
Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...
, or change in response to
heat
In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...
. This term is often used to describe
biochemical substances.
For example, many bacterial
exotoxins are thermolabile and can be easily inactivated by the application of moderate heat.
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
s are also thermolabile and lose their activity when the temperature rises.
Loss of activity in such toxins and enzymes is likely due to change in the three-dimensional structure of the toxin
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
during exposure to heat.
In
pharmaceutical
A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field an ...
compounds, heat generated during grinding may lead to degradation of thermolabile compounds.
This is of particular use in testing
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
function. This is done by intentionally creating
mutant
In biology, and especially in genetics, a mutant is an organism or a new genetic character arising or resulting from an instance of mutation, which is generally an alteration of the DNA sequence of the genome or chromosome of an organism. It ...
s which are thermolabile. Growth below the
permissive temperature
Temperature-sensitive mutants are variants of genes that allow normal function of the organism at low temperatures, but altered function at higher temperatures. Cold sensitive mutants are variants of genes that allow normal function of the organi ...
allows normal protein function, while increasing the temperature above the permissive temperature ablates activity, likely by
denaturing the protein.
Thermolabile
enzymes are also studied for their applications in
DNA replication
In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the most essential part for biological inheritanc ...
techniques, such as
PCR, where
thermostable
In materials science and molecular biology, thermostability is the ability of a substance to resist irreversible change in its chemical or physical structure, often by resisting decomposition or polymerization, at a high relative temperature.
...
enzymes are necessary for proper DNA replication. Enzyme function at higher temperatures may be enhanced with
trehalose
Trehalose (from Turkish '' tıgala'' – a sugar derived from insect cocoons + -ose) is a sugar consisting of two molecules of glucose. It is also known as mycose or tremalose. Some bacteria, fungi, plants and invertebrate animals synthesize it ...
, which opens up the possibility of using normally thermolabile enzymes in DNA replication.
See also
*
Thermostable
In materials science and molecular biology, thermostability is the ability of a substance to resist irreversible change in its chemical or physical structure, often by resisting decomposition or polymerization, at a high relative temperature.
...
*
Thermolabile protecting groups
References
External links
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Biological concepts
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