This article may require cleanup to meet Wikipedia's quality standards. The specific problem is: article lacks important detail (February 2020) (Learn how and when to remove this template message)
|Unit system||SI derived unit|
|In SI base units:||mol/s|
The katal (symbol: kat) is the unit of catalytic activity in the International System of Units (SI). It is a derived SI unit for quantifying the catalytic activity of enzymes (that is, measuring the enzymatic activity level in enzyme catalysis) and other catalysts.
The katal is invariant of the measurement procedure, but the measured numerical value is not; the value depends on the experimental conditions. Therefore, to define the quantity of a catalyst in katals, the rate of conversion of a defined chemical reaction is specified as moles reacted per second. One katal of trypsin, for example, is that amount of trypsin which breaks one mole of peptide bonds in one second under specified conditions.[clarification needed]
One katal refers to an enzyme catalysing the reaction of one mole of substrate per second. Because this is such a large unit for most enzymatic reactions, the nanokatal (nkat) is used in practice.
The katal is not used to express the rate of a reaction; that is expressed in units of concentration per second, as moles per liter per second. Rather, the katal is used to express catalytic activity, which is a property of the catalyst.
|Value||SI symbol||Name||Value||SI symbol||Name|
|10−1 kat||dkat||decikatal||101 kat||dakat||decakatal|
|10−2 kat||ckat||centikatal||102 kat||hkat||hectokatal|
|10−3 kat||mkat||millikatal||103 kat||kkat||kilokatal|
|10−6 kat||µkat||microkatal||106 kat||Mkat||megakatal|
|10−9 kat||nkat||nanokatal||109 kat||Gkat||gigakatal|
|10−12 kat||pkat||picokatal||1012 kat||Tkat||terakatal|
|10−15 kat||fkat||femtokatal||1015 kat||Pkat||petakatal|
|10−18 kat||akat||attokatal||1018 kat||Ekat||exakatal|
|10−21 kat||zkat||zeptokatal||1021 kat||Zkat||zettakatal|
|10−24 kat||ykat||yoctokatal||1024 kat||Ykat||yottakatal|
The General Conference on Weights and Measures and other international organizations recommend use of the katal. It replaces the non-SI enzyme unit of catalytic activity. The enzyme unit is still more commonly used than the katal, especially in biochemistry. The adoption of the katal has been slow.
The name "katal" has been used for decades. The first proposal to make it an SI unit came in 1978, and it became an official SI unit in 1999. The name comes from the Ancient Greek κατάλυσις (katalysis), meaning "dissolution"; the word "catalysis" itself is a Latinized form of the Greek word.
- Nomenclature Committee of the International Union of Biochemistry (NC-IUB) (1979). "Units of Enzyme Activity". Eur. J. Biochem. 97 (2): 319–20. doi:10.1111/j.1432-1033.1979.tb13116.x.
- "Standards for Reporting Enzyme Data: The STRENDA Consortium: What it aims to do and why it should be helpful". Perspectives in Science. 1 (1–6): 131–137. 2014-05-01. doi:10.1016/j.pisc.2014.02.012. ISSN 2213-0209.
- Baltierra-Trejo, Eduardo; Márquez-Benavides, Liliana; Sánchez-Yáñez, Juan Manuel (2015-12-01). "Inconsistencies and ambiguities in calculating enzyme activity: The case of laccase". Journal of Microbiological Methods. 119: 126–131. doi:10.1016/j.mimet.2015.10.007. ISSN 0167-7012.
- "SI Brochure, Table 3: Coherent derived units in the SI with special names and symbols)". Bureau international des poids et mesures (BIPM). Retrieved 2019-05-13.
- Dybkaer, René (March 2002). "The tortuous road to the adoption of katal for the expression of catalytic activity by the General Conference on Weights and Measures". Clinical Chemistry. 48 (3): 586–590. ISSN 0009-9147. PMID 11861460.
- "Units of Enzyme Activity Recommendations 1978". European Journal of Biochemistry. Nomenclature Committee of the International Union of Biochemistry (NC-IUB). 97: 319–320. 1979.
- "UNIT "KATAL" FOR CATALYTIC ACTIVITY (IUPAC Technical Report)" (PDF). Pure and Applied Chemistry. 73 (6): 927–931. 2001.
- "Topic 20: Working with enzymes" (PDF). The Association for Science Education. 2016. Retrieved 31 October 2020.
- Houghton Mifflin Harcourt, The American Heritage Dictionary of the English Language, Houghton Mifflin Harcourt
- Harper, Douglas. "catalysis (n.)". Etymonline. Retrieved 2019-04-03.
- Unit "katal" for catalytic activity (IUPAC Technical Report) Pure Appl. Chem. Vol. 73, No. 6, pp. 927–931 (2001) 
- René Dybkær (1 March 2002). "The Tortuous Road to the Adoption of katal for the Expression of Catalytic Activity by the General Conference on Weights and Measures". Clinical Chemistry. 48 (3): 586–590. doi:10.1093/clinchem/48.3.586. PMID 11861460. Archived from the original on 6 October 2008. Retrieved 8 December 2005.
|This chemistry-related article is a stub. You can help Wikipedia by expanding it.|
|This standards- or measurement-related article is a stub. You can help Wikipedia by expanding it.|