Katal

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The katal (symbol: kat) is the SI unit of catalytic activity. 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.

1 Definition
2 SI multiples
3 Origin
4 External links

[edit] Definition

$k a t = m o l / s$

[edit] SI multiples

Multiple	Name	Symbol	Multiple	Name	Symbol
10⁰	katal	kat
10¹	decakatal	dakat	10^–1	decikatal	dkat
10²	hectokatal	hkat	10^–2	centikatal	ckat
10³	kilokatal	kkat	10^–3	millikatal	mkat
10⁶	megakatal	Mkat	10^–6	microkatal	µkat
10⁹	gigakatal	Gkat	10^–9	nanokatal	nkat
10¹²	terakatal	Tkat	10^–12	picokatal	pkat
10¹⁵	petakatal	Pkat	10^–15	femtokatal	fkat
10¹⁸	exakatal	Ekat	10^–18	attokatal	akat
10²¹	zettakatal	Zkat	10^–21	zeptokatal	zkat
10²⁴	yottakatal	Ykat	10^–24	yoctokatal	ykat

[edit] Origin

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

[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]