GATE 2026 BT – Question 35
You have purified an enzyme using a series of chromatographic methods. It was observed that a 10 $\mu$g mL$^{-1}$ of this purified enzyme converted 10 mM substrate per hour at 25$^o$C and pH 7. Its specific activity is _______ IU $\mu$g$^{-1}$. (rounded off to three decimal places)
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Correct answer: 0.007 to 0.027
Explanation
One IU is 1 $\mu$mol of substrate converted per minute. The rate is 10 mM per hour $= 10\ \mu mol\,mL^{-1}\,h^{-1} = \frac{10}{60} = 0.1667\ \mu mol\,mL^{-1}\,min^{-1}$, which is 0.1667 IU/mL. With 10 $\mu$g of enzyme per mL the specific activity is $\frac{0.1667}{10} = 0.017$ IU/$\mu$g.