In enzymology, a -limonene synthase is 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...

 that catalyzes

Catalysis

Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....

 the chemical reaction

Chemical reaction

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...

geranyl diphosphate (-)-(4S)-limonene + diphosphate

Hence, this enzyme has one substrate

Substrate (biochemistry)

In biochemistry, a substrate is a molecule upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate. In the case of a single substrate, the substrate binds with the enzyme active site, and an enzyme-substrate complex is formed. The substrate is transformed into one or...

, geranyl diphosphate, and two products

Product (chemistry)

Product are formed during chemical reactions as reagents are consumed. Products have lower energy than the reagents and are produced during the reaction according to the second law of thermodynamics. The released energy comes from changes in chemical bonds between atoms in reagent molecules and...

, (-)-(4S)-limonene and diphosphate.

This enzyme belongs to the family of lyase

Lyase

In biochemistry, a lyase is an enzyme that catalyzes the breaking of various chemical bonds by means other than hydrolysis and oxidation, often forming a new double bond or a new ring structure...

s, specifically those carbon-oxygen lyases acting on phosphates. The systematic name of this enzyme class is geranyl-diphosphate diphosphate-lyase [cyclizing, (-)-(4S)-limonene-forming]. Other names in common use include (-)-(4S)-limonene synthase, 4S-(-)-limonene synthase, geranyldiphosphate diphosphate lyase (limonene forming), geranyldiphosphate diphosphate lyase [cyclizing,, and (4S)-limonene-forming]. This enzyme participates in monoterpenoid biosynthesis.