Which enzyme would be best to use in this 25°C experiment given the Kelvin optima listed: Enzyme A: 273 K, Enzyme B: 298 K, Enzyme C: 310 K, Enzyme D: 325 K?

• A. Enzyme A
• B. Enzyme B
• C. Enzyme C
• D. Enzyme D

Answer: (B)

Enzyme activity peaks at a specific temperature, its optimum, where the molecules collide and react most effectively. At 25°C, which is about 298 K, the enzyme whose optimum is 298 K will be at or near its maximum activity.

So the enzyme with a Kelvin optimum of 298 K will perform best under these conditions. The others have optima at 273 K (0°C), 310 K (about 37°C), and 325 K (about 52°C), meaning they would be operating away from their peak performance at 25°C and would react more slowly.