Katal


Katal

The katal (symbol: kat) is the SI unit of catalytic activity. [cite journal |author=Nomenclature Committee of the International Union of Biochemistry (NC-IUB) |title=Units of Enzyme Activity |journal=Eur. J. Biochem. |volume=97 |pages=319–20 |year=1979 |doi = 10.1111/j.1432-1033.1979.tb13116.x] 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.

Definition

kat = mol/s

I multiples

Origin

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

References

External links

* Unit "katal" for catalytic activity (IUPAC Technical Report) "Pure Appl. Chem." Vol. 73, No. 6, pp. 927-931 (2001) [http://www.iupac.org/publications/pac/2001/7306/7306x0927.html]

* 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. [http://www.clinchem.org/cgi/content/full/48/3/586]


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Look at other dictionaries:

  • Katal — (símbolo kat) es una unidad derivada del SI para la actividad catalítica. Definida como moles por segundo. El nombre katal ha sido usado desde hace tiempo, pero no se hizo oficial en el SI hasta 1999. En cinética enzimática, es la cantidad de… …   Enciclopedia Universal

  • katal — См. kat. Diccionario Mosby Medicina, Enfermería y Ciencias de la Salud, Ediciones Hancourt, S.A. 1999 …   Diccionario médico

  • katal — /katˈl/ noun A derived SI unit, the unit of catalytic activity (symbol kat), equal to one mole per second ORIGIN: Appar from Gr katalysis catalysis …   Useful english dictionary

  • Katal — Einheit Norm SI Einheitensystem Einheitenname Katal Einheitenzeichen kat Beschriebene Größe(n) katalytische Aktivität Größensymbol(e) …   Deutsch Wikipedia

  • Katal — Sur les autres projets Wikimedia : « Katal », sur le Wiktionnaire (dictionnaire universel) Le katal (symbole kat) est une unité introduite en octobre 1999 dans le système SI par la 21e Conférence générale des poids et mesures, pour …   Wikipédia en Français

  • Katal — El katal (símbolo kat) es una unidad derivada del Sistema Internacional de Unidades para medir la actividad catalítica, especialmente en los campos de medicina y bioquímica. Es definido como la actividad catalítica responsable de la… …   Wikipedia Español

  • Katal — katalas statusas T sritis Standartizacija ir metrologija apibrėžtis Katalizinio aktyvumo išvestinio SI matavimo vieneto specialus pavadinimas. Vienas katalas – tai fermento kiekis, katalizuojantis 1 mol substrato virtimą produktu per 1 s… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • katal — katalas statusas T sritis Standartizacija ir metrologija apibrėžtis Katalizinio aktyvumo išvestinio SI matavimo vieneto specialus pavadinimas. Vienas katalas – tai fermento kiekis, katalizuojantis 1 mol substrato virtimą produktu per 1 s… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • katal — katalas statusas T sritis chemija apibrėžtis Fermento kiekis, katalizuojantis 1 molio substrato virtimą produktu per 1 s optimaliomis sąlygomis (1 kat = 6·10⁷ fermento aktyvumo vienetų). santrumpa( os) kat atitikmenys: angl. katal rus. катал …   Chemijos terminų aiškinamasis žodynas

  • katal — (kat)    a unit of catalytic activity used especially in the chemistry of enzymes.    A catalyst is a substance that starts or speeds a chemical reaction. Enzymes are proteins that act as catalysts within the bodies of living plants and animals.… …   Dictionary of units of measurement


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