Katal

For the village, see Katal, Iran.

katal
Unit system	SI
Unit of	catalysis
Symbol	kat
In SI base units:	mol/s

The katal (symbol: kat) is that catalytic activity that will raise the rate of conversion by one mole per second in a specified assay system. ^[1] It is a unit of the International System of Units (SI) ^[1] used for quantifying the catalytic activity of enzymes (that is, measuring the enzymatic activity level in enzyme catalysis) and other catalysts.

The unit "katal" is not attached to a specified measurement procedure or assay condition, but any given catalytic activity is: the value measured depends on experimental conditions that must be specified. ^{[2] [3]} Therefore, to define the quantity of a catalyst in katals, the catalysed rate of conversion (the rate of conversion in presence of the catalyst minus the rate of spontaneous conversion) of a defined chemical reaction is measured in moles per second. ^[4] One katal of trypsin, for example, is that amount of trypsin which breaks one mole of peptide bonds in one second under the associated specified conditions.^{[ clarification needed ]}

Definition

One katal refers to an amount of enzyme that gives a catalysed rate of conversion of one mole per second. ^{[5] [6]} Because this is such a large unit for most enzymatic reactions, the nanokatal (nkat) is used in practice. ^[6]

${\displaystyle {\text{kat}}={\frac {\text{mol}}{\text{s}}}}$

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.

SI multiples

SI multiples of katal (kat)

Submultiples			Multiples
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
10−27 kat	rkat	rontokatal	1027 kat	Rkat	ronnakatal
10−30 kat	qkat	quectokatal	1030 kat	Qkat	quettakatal

History

The General Conference on Weights and Measures and other international organizations recommend use of the katal. ^[7] It replaces the non-SI enzyme unit of catalytic activity. The enzyme unit is still more commonly used than the katal, ^[6] especially in biochemistry.^{[ citation needed ] [8]} The adoption of the katal has been slow. ^{[6] [9]}

Origin

The name "katal" has been used for decades. The first proposal to make it an SI unit came in 1978, ^{[6] [10]} and it became an official SI unit in 1999. ^{[6] [11] [12]} The name comes from the Ancient Greek κατάλυσις (katalysis), meaning "dissolution"; ^[13] the word "catalysis" itself is a Latinized form of the Greek word. ^{[13] [14]}

References

1. Nomenclature Committee of the International Union of Biochemistry (NC-IUB) (1979). "Units of Enzyme Activity". European Journal of Biochemistry. 97 (2): 319–20. doi: 10.1111/j.1432-1033.1979.tb13116.x .
2. Dybkær, R. (1979). "Approved recommendation (1978) quantities and units in clinical chemistry". Clinica Chimica Acta. 96 (1): 157–183. doi:10.1016/0009-8981(79)90065-2. ISSN   0009-8981.
3. BIPM (2019). Le Système international d’unités / The International System of Units (‘The SI Brochure’) (9e ed.). Bureau international des poids et mesures. ISBN   978-92-822-2272-0.
4. Dybkær, René (2001). "UNIT "KATAL" FOR CATALYTIC ACTIVITY (IUPAC Technical Report)" (PDF). Pure and Applied Chemistry. 73 (6): 927–931. doi:10.1351/pac200173060927. S2CID   195819612.
5. Tipton, Keith F.; Armstrong, Richard N.; Bakker, Barbara M.; Bairoch, Amos; Cornish-Bowden, Athel; Halling, Peter J.; Hofmeyr, Jan-Hendrik; Leyh, Thomas S.; Kettner, Carsten; Raushel, Frank M.; Rohwer, Johann; Schomburg, Dietmar; Steinbeck, Christoph (2014-05-01). "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. doi: 10.1016/j.pisc.2014.02.012 . ISSN   2213-0209.
6. 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. PMID   26459230.
7. "SI Brochure, Table 3: Coherent derived units in the SI with special names and symbols)". Bureau international des poids et mesures (BIPM). Archived from the original on 2019-03-21. Retrieved 2019-05-13.
8. Dybkaer, Rene (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): 586–90. PMID   11861460 – via National Library of Medicine, National Center for Biotechnology information.
9. 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. doi: 10.1093/clinchem/48.3.586 . ISSN   0009-9147. PMID   11861460.
10. "Units of Enzyme Activity Recommendations 1978". European Journal of Biochemistry. 97 (2). Nomenclature Committee of the International Union of Biochemistry (NC-IUB): 319–320. 1979. doi: 10.1111/j.1432-1033.1979.tb13116.x .
11. Dybkær, René (2001). "UNIT "KATAL" FOR CATALYTIC ACTIVITY (IUPAC Technical Report)" (PDF). Pure and Applied Chemistry. 73 (6): 927–931. doi:10.1351/pac200173060927. S2CID   195819612.
12. "Topic 20: Working with enzymes" (PDF). The Association for Science Education. 2016. Retrieved 31 October 2020.
13. Houghton Mifflin Harcourt, The American Heritage Dictionary of the English Language, Houghton Mifflin Harcourt
14. Harper, Douglas. "catalysis (n.)". Etymonline. Retrieved 2019-04-03.

External links

• 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.