pro·​te·​ase | \ ˈprō-tē-ˌās How to pronounce protease (audio) , -ˌāz \

Definition of protease

: any of numerous enzymes that hydrolyze proteins and are classified according to the most prominent functional group (such as serine or cysteine) at the active site

called also proteinase

Examples of protease in a Sentence

Recent Examples on the Web Paxlovid is a made up of two protease inhibitors, including one used in treating HIV as a booster medicine. Patrick Jackson, The Conversation, 28 Apr. 2022 That’s one reason that, from the start, the team planned to combine their medicine with ritonavir, which is commonly used with protease inhibitors to treat HIV to increase blood levels of drug. Matthew Herper, STAT, 28 Apr. 2022 The early Pfizer laboratory tests showed that Paxlovid blocked the protease enzyme in Omicron, as well as other variants of concern, Dr. Dolsten said. Jared S. Hopkins, WSJ, 14 Dec. 2021 While drugs that initially seemed promising fell short, by the mid-90s, protease inhibitors slashed virus levels and delivered a medical miracle. New York Times, 25 Mar. 2022 The drugs, called protease inhibitors, block the replication of the AIDS-causing virus by chemically binding a key enzyme. Merrie Monteagudo, San Diego Union-Tribune, 15 Mar. 2022 This processing is needed before the virus is able to copy its own genome, so inhibiting the protease should block viral reproduction. John Timmer, Ars Technica, 15 Dec. 2021 The drug, originally called PF-00835231, lodged in the protease like a piece of gum crammed between scissor blades. New York Times, 7 Dec. 2021 The nirmatrelvir in the pill blocks the activity of SARS-CoV-2-3CL protease, a particular enzyme the virus needs in order to replicate, Pfizer explains. Korin Miller,, 14 Dec. 2021 See More

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

First Known Use of protease

1903, in the meaning defined above

History and Etymology for protease

borrowed from French protéase, from protéine protein + -ase -ase

Note: The French term was probably introduced by the Italian microbiologist and philosopher Giovanni Malfitano (1872-1941) in "Sur le protéase de l'Aspergillus niger," Annales de l'Institut Pasteur, tome quatorzième (1900), p. 420. The term protease was used in English without attribution to Malfitano and perhaps coined independently by the British botanist Sydney Howard Vines (1849-1934) in "Proteolytic Enzymes in Plants," Annals of Botany, vol. 17, no. 65 (January, 1903), p. 237.

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The first known use of protease was in 1903

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Dictionary Entries Near protease



protease inhibitor

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Last Updated

11 May 2022

Cite this Entry

“Protease.” Dictionary, Merriam-Webster, Accessed 23 May. 2022.

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More Definitions for protease


pro·​te·​ase | \ ˈprōt-ē-ˌās, -ˌāz How to pronounce protease (audio) \

Medical Definition of protease

: any of numerous enzymes that hydrolyze proteins and are classified according to the most prominent functional group (as serine or cysteine) at the active site

called also proteinase

— compare peptidase

More from Merriam-Webster on protease Encyclopedia article about protease


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