Katal

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The katal (symbol: kat) is the SI unit of catalytic activity.^[1] It is a derived SI unit for expressing quantity values of catalytic activity of enzymes and other catalysts. Its use is recommended by the General Conference on Weights and Measures and other international organizations. It replaces the non-SI enzyme unit. Enzyme units are, however, still more commonly used than the katal in practice at present, especially in biochemistry.

The katal is not used to express the rate of a reaction; that is expressed in moles per second. Rather, it is used to express catalytic activity which is a property of the catalyst. The katal is invariant of the measurement procedure, but the numerical quantity value is not and depends on the experimental conditions. Therefore, in order to define the quantity of a catalyst, the rate of conversion of a defined chemical reaction has to be specified, preferably of the first order, under strictly controlled conditions. One katal of trypsin, for example, is that amount of trypsin which breaks a mole of peptide bonds per second under specified conditions.

Contents 1 Definition 2 SI multiples 3 Origin 4 References 5 External links

[edit] Definition

kat = mol / s

[edit] SI multiples

SI multiples for katal (kat)

Submultiples				Multiples
Value	Symbol	Name		Value	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

[edit] Origin

The name katal has been used for decades and it became an official SI unit in 1999.

[edit] References

[edit] External links

• Unit "katal" for catalytic activity (IUPAC Technical Report) Pure Appl. Chem. Vol. 73, No. 6, pp. 927-931 (2001) [1]

• The Tortuous Road to the Adoption of katal for the Expression of Catalytic Activity by the General Conference on Weights and Measures (Clinical Chemistry. (2002) Vol. 48, pp. 586-590. [2]