Thermolabile refers to a substance which is subject to, decomposition, or change in response to heat.
[1] For example, many bacterial exotoxins are thermolabile and can be easily inactivated by the application of moderate heat.
Enzymes are also thermolabile and lose their activity when the temperature rises.
Thermolabile enzymes are also studied for their applications in DNA replication techniques, such as PCR, where thermostable enzymes are necessary for proper DNA replication.
Enzyme function at higher temperatures may be enhanced with trehalose, which opens up the possibility of using normally thermolabile enzymes in DNA replication.