Question

10) What relative values of Km and kcat would describe an enzyme with a high catalytic efficiency?

a) Low Km low kcat

b) High Km High kcat

c) Low Km high kcat

d) High Km low kcat​

Answer 1

Answer:

a) low km low kcat

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Answer 2

Low Km high kcat describes an enzyme with high catalytic efficiency.

(option - c)

• The catalytic efficiency of an enzyme is given by the following formula:-            

• Catalytic efficiency = kcat/km.
• According to the formula:

1. Kcat is directly proportional to catalytic efficiency, therefore increasing Kcat leads to high catalytic efficiency.
2. Km is inversely proportional to Kcat, therefore decreasing Km leads to high catalytic efficiency.  

• Km is defined as the substrate concentration at half Vmax.

• Vmax is the maximal enzyme rate - the velocity at which the catalysis rate is highest.
• Kcat is called the turnover number - it defines the number of substrate molecules converted by the enzyme to the product in 1 minute per enzyme site.