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A combination of KM and kcat with which relative values is indicative of the lowest catalytic efficiency for an enzymatically catalyzed reaction?

a. A high Km and a low kcat
b. A high Km and a high kcat
c. A low Km and a high kcat
d. A low Km and a low kcat

1 Answer

6 votes

Answer:

option a

Step-by-step explanation:


k_(cat) is turnover number. The turnover number is defined as the number of chemical conversions by single enzymatic site per second.

K_m is Michaelis-Menten constant used in the study of kinetics of enzyme catalyzed reaction.

The relationship between Michaelis-Menten constant and turnover number is as follows:


v=k_(cat)[E_0]([S])/(K_m+[S])

Here, [S] is substrate concentration, E0 is the initial enzyme concentration and v is the rate of enzyme catalyzed reaction.

Turn over no. (
k_(cat)) is present in nominator while K_m is present in denominator. Therefore for lowest catalytic efficiency, turnover (
k_(cat)) should be low and Michaelis-Menten constant (K_m) should be high.

Therefore, among, given option a is correct.

User Ouerghi Yassine
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