An adaptive enzyme or inducible enzyme is an

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

that is expressed only under conditions in which it is clearly of adaptive value, as opposed to a

constitutive enzyme Gene expression is the process (including its regulation) by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, proteins or non-coding RNA, and ultimately affect a pheno ...

which is produced all the time. The inducible enzyme is used for the breaking-down of things in the cell. It is also a part of the Operon Model, which illustrates a way for genes to turn "on" and "off". The inducer causes the gene to turn on (controlled by the amount of reactant which turns the gene on). Then there's the repressor protein that turns genes off. The inducer can remove this repressor, turning genes back on. The operator is a section of DNA where the repressor binds to shut off certain genes; the promoter is the section of DNA where the

RNA polymerase In molecular biology, RNA polymerase (abbreviated RNAP or RNApol), or more specifically DNA-directed/dependent RNA polymerase (DdRP), is an enzyme that catalyzes the chemical reactions that synthesize RNA from a DNA template. Using the e ...

binds. Lastly, the regulatory gene is the gene for the repressor protein. An example of inducible enzyme is

COX-2 Cyclooxygenase-2 (COX-2), also known as prostaglandin-endoperoxide synthase 2 ( HUGO PTGS2), is an enzyme that in humans is encoded by the ''PTGS2'' gene. In humans it is one of three cyclooxygenases. It is involved in the conversion of arachid ...

which is synthesized in

macrophages Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that ...

to produce prostaglandin E₂ while the

COX-1 Cyclooxygenase 1 (COX-1), also known as prostaglandin-endoperoxide synthase 1 ( HUGO PTGS1), is an enzyme that in humans is encoded by the ''PTGS1'' gene. In humans it is one of three cyclooxygenases. History Cyclooxygenase (COX) is the centr ...

(another isozyme in

COX Cox or COX may refer to: Companies * Cox Enterprises, a media and communications company ** Cox Communications, cable provider ** Cox Media Group, a company that owns television and radio stations ** Cox Automotive, an Atlanta-based busines ...

family) is always produced in variety of organs in body (like stomach).

References

Enzymes {{Enzyme-stub