Units of catalytic-activity (Enzyme Activity)
| Definition | Amount of enzyme that catalyses the transformation of certain moles of substrate per time unit under standard conditions (ref. 1) |
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| Scope | Two corresponding units to catalytic-activity (enzyme activity) exist |
| Recommendation |
Katal is the recommended unit for catalytic-activity kind-of-quantity (ref. 2) Note: The unit symbol “IU” which refers to WHO International Unit is not a corresponding unit for catalytical-activity but for a biological activity. This maay be expressed as e.g. arbitrary substance concentration. |
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| Symbol | Kat |
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| Definition |
The amount of enzyme that catalyses the transformation of one mole of substrate per second under standard conditions kat=mol/s |
| Recommendation | Recommended unit for use of catalytic-activity kind-of-quantity |
| Reference |
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| Symbol | U |
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| Definition |
The amount of enzyme that catalyses the transformation of one micromol of substrate per minute under standard conditions U=µmol/min |
| Scope | Unit for use of catalytic-activity kind-of-quantity |
| Caution | Due to the symbol, U, the symbol can be mistaken by International Unit (IU) that is a non-SI unit |
| Non-recommended term | International Unit (IU) |
| Reference |
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