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Enzyme efficiency is measured by KM                  b. kcat/ KM                 &n

  1. Enzyme efficiency is measured by
    1. KM                  b. kcat/ KM                   c. kcat               d. ½ Vmax
  1. The KM values in mM for a hexokinase with different substrates is:

glucose = 3.4       fructose =2.3            galactose = 0.5            gulose = 1.3

The highest activity for the enzyme takes place with the substrate

  1. glucose            b. fructose           c. galactose                     d. gulose
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Answer #1

Enzyme efficiency is measured by (b) Kcat / KM .

The Kcat is the number of reactions that can occur by a single enzyme per unit second of time in proper conditions , whereas the km is the Michaelis Menton constant which is the concentration of the substrate at which the reaction velocity is half it's maximal velocity.

The lower the value of km ,the higher will be the affinity of the enzyme to the substrate ,so the rate of the reaction is higher with the substrate which having the least value of the km value .

In the given substrates the galactose having the least value that is 0.5 so the fastest activity of the enzyme hexokinase is with the galactose .  

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