Question

An enzyme is discovered that catalyzes the chemical reaction CALM \(\rightleftharpoons\) ANGER. A team of motivated researchers sets out to study the enzyme, which they called Angerase. They find that the \( \text{K}_{cat} \) (constant) for Angerase is \( 600 \, \text{s}^{-1} \). Some experiments were done. In one such experiment when [\( \text{E}_t \)] (total enzyme concentration) \( = 20 \, \text{nM} \) and [CALM] \( = 40 \, \mu\text{M} \), the reaction velocity, \( \text{V}_0 \) is \( 9.6 \, \mu\text{M s}^{-1} \), calculate Km (Michaelis constant) for the substrate 'CALM'.

• A. 90 \(\mu\)M
• B. 200 \(\mu\)M
• C. 10 \(\mu\)M
• D. 0.8 \(\mu\)M

Hint:

Always ensure concentration units match before plugging them into the Michaelis-Menten equation. Converting nM (Total Enzyme) to \(\mu\)M prevents massive calculation errors.
\( 20 \, \text{nM} = 0.02 \, \mu\text{M} \). Then \( V_{max} = 600 \times 0.02 = 12 \, \mu\text{M s}^{-1} \). Much faster!

Answer 1

The Correct Option is C