What is the conversion factor between International Units (IU) and nano katal (nkat)?

What is the conversion factor between International Units (IU) and nano katal (nkat)?

• A. 1 IU = 17 nkat
• B. 1 IU = 1 nkat
• C. 1 IU = 0.17 nkat
• D. 1 IU = 170 nkat

Answer: (A)

The key idea is converting enzyme activity from per minute to per second and then to nano-scale units. An International Unit (IU) is defined as the amount of enzyme that catalyzes the transformation of 1 micromole of substrate per minute. A katal (kat) is 1 mole of substrate per second, so relate the two by time. 1 µmol/min equals 1e-6 mol divided by 60 s = 1.666...e-8 mol/s, which is 1.666...e-8 kat. To express this in nano-kat, multiply by 1e9, giving 16.666... nkat. Rounding yields about 17 nkat per IU. So the conversion is roughly 1 IU ≈ 17 nkat.

The key idea is converting enzyme activity from per minute to per second and then to nano-scale units. An International Unit (IU) is defined as the amount of enzyme that catalyzes the transformation of 1 micromole of substrate per minute. A katal (kat) is 1 mole of substrate per second, so relate the two by time.

1 µmol/min equals 1e-6 mol divided by 60 s = 1.666...e-8 mol/s, which is 1.666...e-8 kat. To express this in nano-kat, multiply by 1e9, giving 16.666... nkat. Rounding yields about 17 nkat per IU. So the conversion is roughly 1 IU ≈ 17 nkat.