# Katal

Katal
Unit systemSI derived unit
Unit ofcatalysis
Symbolkat
In SI base units:mol/s

The katal (symbol: kat) is the unit of catalytic activity in the International System of Units (SI).[1] 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 General Conference on Weights and Measures and other international organizations recommend use of the katal.[citation needed] It replaces the non-SI enzyme unit of catalytic activity. Enzyme units are, however, still more commonly used than the katal, especially in biochemistry.[citation needed]

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.

The katal is invariant of the measurement procedure, but the measured numerical value is not; the value depends on the experimental conditions.[citation needed] 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.[citation needed] One katal of trypsin, for example, is that amount of trypsin which breaks one mole of peptide bonds in one second under specified conditions.

## Definition[]

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

## SI multiples[]

Submultiples Multiples Value SI symbol Name Value 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

## Origin[]

The name "katal" has been used for decades, and the unit became an official SI unit in 1999. The name comes from the Ancient Greek κατάλυσις (katalysis), meaning "dissolution",[2]; the word "catalysis" itself is a Latinized form of the Greek word.[2][3]

## References[]

1. ^ 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.
2. ^ a b Houghton Mifflin Harcourt, The American Heritage Dictionary of the English Language, Houghton Mifflin Harcourt
3. ^ Harper, Douglas. "catalysis (n.)". Etymonline. Retrieved 2019-04-03.