active site


Definition of active site

: a region on the surface of an enzyme whose shape permits binding only of a specific molecular substrate that then undergoes catalysis

Examples of active site in a Sentence

Recent Examples on the Web As the chain gets progressively longer, its ability to fit into the active site of the enzymes gradually gets worse. John Timmer, Ars Technica, "Researchers completely re-engineer yeast to make more biofuel," 20 Jan. 2020 Including this project, Brasfield & Gorrie has four active sites in Cary. William Thornton |, al, "Brasfield & Gorrie breaks ground on North Carolina project," 21 Nov. 2019 Neither charter school has an active site within those districts, but instead has locations in other districts, including Grossmont Union High School District. San Diego Union-Tribune, "Three Learn4Life charter school sites will be shut down on judge’s order," 12 June 2019 The park, which borders LACMA, also remains an active site for scientific research, with paleontologists excavating there 361 days a year. Julia Wick,, "Essential California: A new face for the La Brea Tar Pits on a changing Wilshire Boulevard," 7 June 2019 The two churches were able to retain their names and will continue as active sites of the new parish. Maryann Pisano,, "'The Fourth of July brings everyone together': Newly united parish among 75 entrants in Elmwood Park parade," 7 July 2018 The nation’s active sites get an average of 8,700 requests to access their stocks annually, according to Peter Bretting, who oversees the system. Sena Christian, Newsweek, "Breakfast in Post-Apocalypse America: Inside Colorado's Fort Knox of Food," 19 Nov. 2015 Citrus samples are sent from the USDA active site collection in Riverside, California. Sena Christian, Newsweek, "Breakfast in Post-Apocalypse America: Inside Colorado's Fort Knox of Food," 19 Nov. 2015 This method revealed five particular amino acids that comprise the likely active site. Diana Gitig, Ars Technica, "A randomly generated, totally novel enzyme rescues mutant bacteria," 20 Jan. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'active site.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of active site

1957, in the meaning defined above

Keep scrolling for more

Learn More about active site

Time Traveler for active site

Time Traveler

The first known use of active site was in 1957

See more words from the same year

Statistics for active site

Cite this Entry

“Active site.” Dictionary, Merriam-Webster, Accessed 22 Jan. 2021.

Keep scrolling for more

More Definitions for active site

active site


Medical Definition of active site

: a region especially of a biologically active protein (as an enzyme) where catalytic activity takes place and whose shape permits the binding only of a specific reactant molecule

More from Merriam-Webster on active site Encyclopedia article about active site

Comments on active site

What made you want to look up active site? Please tell us where you read or heard it (including the quote, if possible).


Test Your Vocabulary

Slippery Words Quiz—Changing with the Times

  • ducreux self portrait yawning
  • What is an earlier meaning of nice?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

Universal Daily Crossword

A daily challenge for crossword fanatics.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!