Enzyme unit
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2008-06-21T11:37:14Z
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The '''enzyme unit''' (U) is a [[unit of measurement|unit]] for the amount of a particular [[enzyme]].<ref>{{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 |url=http://www.blackwell-synergy.com/doi/pdf/10.1111/j.1432-1033.1979.tb13116.x |doi=10.1111/j.1432-1033.1979.tb13116.x <!--Retrieved from URL by DOI bot-->}}</ref>
One U is defined as that amount of the enzyme that [[catalysis|catalyzes]] the conversion of 1 [[micro]] [[mole (unit)|mole]] of [[substrate (biochemistry)|substrate]] per minute. The conditions also have to be specified: one usually takes a temperature of 30°C and the [[pH value]] and substrate concentration that yield the maximal substrate conversion rate.
The enzyme unit was adopted by the [[International Union of Biochemistry and Molecular Biology|International Union of Biochemistry]] in 1964. Since the minute is not an [[SI]] unit, the enzyme unit is discouraged in favour of the [[katal]], the unit recommended by the [[General Conference on Weights and Measures]] in 1978 and officially adopted in 1999. One katal is the amount of enzyme that converts 1 mole of substrate per second, so
:1 U = 1/60 micro katal = 16.67 nano katal.
The enzyme unit should not be confused with the [[International Unit]] (IU), an unrelated measure of biologically active substances.
==See also==
*[[Enzyme assay]]
*[[Enzyme catalysis]]
==References==
{{reflist}}
[[Category:Units of catalytic activity]]
[[de:Enzymeinheit]]
[[ja:ユニット (酵素活性)]]
[[pl:Jednostka enzymu]]
[[sk:Enzýmová jednotka]]