Substrate

Synonyms

Substratum

Definition

In chemistry, a substrate is a substance that is acted upon by a catalyst.

History

The word substrate is a composite of the Latin terms sub “below” and stratum “layer”.

Overview

In modern organisms, protein- or RNA-based polymers (enzymes and ribozymes, respectively) serve as catalysts that act upon various substrates, or reactants, which can be organic or inorganic. Substrates and catalysts are usually distinct entities, and depending on the reaction in question, a catalyst may react with two substrates together simultaneously or act promiscuously on various structurally related substrates.

In the case of a single substrate, the substrate binds with the enzyme or catalyst active site, and a catalyst-substrate complex is formed. The substrate is then catalytically transformed into one or more products, which are then released from the active site.

$$ \mathrm{C}+\mathrm{S}\rightleftharpoons \mathrm{C}\mathrm{S}\to \mathrm{C}\mathrm{P}\rightleftharpoons...