Enzyme induction is a process in which a molecule

Molecule

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 (e.g. a drug) induces (i.e. initiates or enhances) the expression

Gene expression

Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as ribosomal RNA , transfer RNA or small nuclear RNA genes, the product is a functional RNA...

 of an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

.

Enzyme inhibition can refer to

• the inhibition of the expression of the enzyme by another molecule
• interference at the enzyme-level
  Enzyme inhibitor
  An enzyme inhibitor is a molecule that binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides...
  
  , basically with how the enzyme works. This can be competitive inhibition
  Competitive inhibition
  Competitive inhibition is a form of enzyme inhibition where binding of the inhibitor to the active site on the enzyme prevents binding of the substrate and vice versa.-Mechanism:...
  
  , uncompetitive inhibition, non-competitive inhibition
  Non-competitive inhibition
  Non-competitive inhibition is a type of enzyme inhibition where the inhibitor reduces the activity of the enzyme, by binding not to the active site on the enzyme, but to a different site...
  
   or partially competitive inhibition.

If the molecule induces enzymes that are responsible for its own metabolism

Metabolism

Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

, this is called auto-induction (or auto-inhibition if there is inhibition). These processes are particular forms of gene expression regulation

Regulation of gene expression

Gene modulation redirects here. For information on therapeutic regulation of gene expression, see therapeutic gene modulation.Regulation of gene expression includes the processes that cells and viruses use to regulate the way that the information in genes is turned into gene products...

.

These terms are of particular interest to pharmacology

Pharmacology

Pharmacology is the branch of medicine and biology concerned with the study of drug action. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function...

, and more specifically to drug metabolism

Drug metabolism

Drug metabolism is the biochemical modification of pharmaceutical substances by living organisms, usually through specialized enzymatic systems. This is a form of xenobiotic metabolism. Drug metabolism often converts lipophilic chemical compounds into more readily excreted polar products...

 and drug interaction

Drug interaction

A drug interaction is a situation in which a substance affects the activity of a drug, i.e. the effects are increased or decreased, or they produce a new effect that neither produces on its own. Typically, interaction between drugs come to mind...

s. They also apply to molecular biology

Molecular biology

Molecular biology is the branch of biology that deals with the molecular basis of biological activity. This field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...

.

History

In the late 1950s and early 1960s, the French molecular biologists François Jacob

François Jacob

François Jacob is a French biologist who, together with Jacques Monod, originated the idea that control of enzyme levels in all cells occurs through feedback on transcription. He shared the 1965 Nobel Prize in Medicine with Jacques Monod and André Lwoff.-Childhood and education:François Jacob is...

 and Jacques Monod

Jacques Monod

Jacques Lucien Monod was a French biologist who was awarded a Nobel Prize in Physiology or Medicine in 1965, sharing it with François Jacob and Andre Lwoff "for their discoveries concerning genetic control of enzyme and virus synthesis"...

 became the first to explain enzyme induction, in the context of the lac operon

Lac operon

The lac operon is an operon required for the transport and metabolism of lactose in Escherichia coli and some other enteric bacteria. It consists of three adjacent structural genes, lacZ, lacY and lacA. The lac operon is regulated by several factors including the availability of glucose and of...

 of Escherichia coli

Escherichia coli

Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...

. In the absence of lactose, the constitutively expressed lac repressor

Lac repressor

The lac repressor is a DNA-binding protein which inhibits the expression of genes coding for proteins involved in the metabolism of lactose in bacteria. These genes are repressed when lactose is not available to the cell, ensuring that the bacterium only invests energy in the production of...

 protein binds to the operator region of the DNA and prevents the transcription of the operon genes. When present, lactose binds to the lac repressor, causing it to separate from the DNA and thereby enabling transcription to occur. Monod and Jacob generated this theory following 15 years of work by them and others (including Joshua Lederberg

Joshua Lederberg

Joshua Lederberg ForMemRS was an American molecular biologist known for his work in microbial genetics, artificial intelligence, and the United States space program. He was just 33 years old when he won the 1958 Nobel Prize in Physiology or Medicine for discovering that bacteria can mate and...

), partially as an explanation for Monod's observation of diauxie

Diauxie

Diauxie is a French word coined by Jacques Monod to mean two growth phases. The word is used in English in cell biology to describe the growth phases of a microorganism in batch culture as it metabolizes a mixture of two sugars...

. Previously, Monod had hypothesized that enzymes could physically adapt themselves to new substrates; a series of experiments by him, Jacob, and Arthur Pardee

Arthur Pardee

Arthur Pardee is an American biochemist. One biographical portrait begins "Among the titans of science, Arthur Pardee is especially intriguing." There is hardly a field of molecular biology that is not affected by his work, which has advanced our understanding through theoretical predictions...

 eventually demonstrated this to be incorrect and led them to the modern theory, for which he and Jacob shared the 1965 Nobel Prize in Physiology or Medicine

Nobel Prize in Physiology or Medicine

The Nobel Prize in Physiology or Medicine administered by the Nobel Foundation, is awarded once a year for outstanding discoveries in the field of life science and medicine. It is one of five Nobel Prizes established in 1895 by Swedish chemist Alfred Nobel, the inventor of dynamite, in his will...

 (together with André Lwoff).

• Aryl hydrocarbon receptor
  Aryl hydrocarbon receptor
  The Aryl hydrocarbon receptor is a member of the family of basic-helix-loop-helix transcription factors. AhR is a cytosolic transcription factor that is normally inactive, bound to several co-chaperones...