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enzyme units and IU - (Sep/21/2006 )


whts the difference between enzyme units and enzyme international units. how we have to convert units to IU


I always thought that each enzyme had a given amount of units.

Never knew abt International units.


each provider has its own idea of "units"; what is "milli-U" for one supllier is "U" for another; look in each special case for the definition of "U" or "IU" even of same enzymes but from different sources; the definition is the bottom line; it might differ in decimal powers

-The Bearer-

In biochemistry an International Unit for enzyme activity is: "One unit is the amount of enzyme activity which will catalyse the transformation of 1 micromole of the substrate per minute under standard conditions."
In molecular biology its more complicated, I also would always look at the suppliers description as mentioned before, as every enzyme type has its own and as they can differ between companies.
But the above definition should be appilcable in most cases also to these enzymes (restr. enzymes, nucleases, ligases, etc.) but probably not useful ?? No idea.


is it IU=U/ml????

-T. reesei-

QUOTE (T. reesei @ Nov 15 2006, 04:24 AM)
is it IU=U/ml????

no. iu is amount, u/ml is concentration.


then it shoud be IU=U/mg?????

-T. reesei-

QUOTE (T. reesei @ Nov 15 2006, 08:20 PM)
then it shoud be IU=U/mg?????

no. iu is amount of activity, u/mg is specific activity (a measure of purity).


thankx to clear the confusionsssss

-T. reesei-

Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, the products. Almost all processes in a biological cell need enzymes to occur at significant rates. Since enzymes are selective for their substrates and speed up only a few reactions from among many possibilities, the set of enzymes made in a cell determines which metabolic pathways occur in that cell.
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