Enzyme

Article By:

Wellner, Daniel Department of Biochemistry, Cornell University Medical College, Ithaca, New York.

Last reviewed:November 2021

DOI:https://doi.org/10.1036/1097-8542.236000

Show previous versions

• Enzyme, published April 2021:Download PDF Get Adobe Acrobat Reader
• Enzyme, published October 2016:Download PDF Get Adobe Acrobat Reader

A catalytic protein produced by living cells. Chemical reactions involved in the digestion of foods, the biosynthesis of macromolecules, the controlled release and utilization of chemical energy, and other processes characteristic of life are all catalyzed by enzymes (Fig. 1). Hundreds of reactions can proceed simultaneously within a living cell, and the cell contains a comparable number of individual enzymes, each of which controls the rate of one or more of these reactions. In the absence of enzymes, these reactions would not take place at a significant rate. Indeed, enzymes are such efficient catalysts that they accelerate chemical reactions measurably even at concentrations too low to be detected by most protein assays. In addition, enzymes promote the chemical processes of life without being themselves altered or destroyed. See also: Catalysis and catalysts; Cell biology; Cytochemistry; Protein

The content above is only an excerpt.