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Old 01-05-2014
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Default enzyme kinetics..

consider a reaction that can be catalyzed by one of two enzymes, A and B, with the following kinetics,

Km (M) Vmax (mmmol/min)
A. 5 x 10-6 20
B. 5 x 10-4 30

6. At concentration of 5x10-4 M substrate, the velocity of the reaction catalyzed by enzyme A will be

A. 10
B. 15
C. 20
D. 25
E. 30



kindly answer with explanation because i'm just stuck with this....your response will be appreciated.. thankuu
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Old 01-06-2014
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first of all rule out the last two options because the enzyme cant work beyond it Vmax which is 20.
then rule out the first option bcoz thats the velocity at Km i.e 5 x10-6 .
u r left with B and C now the value 5 x 10-4 is far above the Km so i m `guessing` the enzyme is working at its Vmax. they dont expect you to solve the complicated calculations on exam but if you want to make sure then solve the problem with lineweaver-burk equation and u will get the answer C. 20
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Old 01-07-2014
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Quote:
Originally Posted by slacker.mle View Post
first of all rule out the last two options because the enzyme cant work beyond it Vmax which is 20.
then rule out the first option bcoz thats the velocity at Km i.e 5 x10-6 .
u r left with B and C now the value 5 x 10-4 is far above the Km so i m `guessing` the enzyme is working at its Vmax. they dont expect you to solve the complicated calculations on exam but if you want to make sure then solve the problem with lineweaver-burk equation and u will get the answer C. 20
i understood that Vmax of A =20 so at Km its 20/2= 10,
but i didnt get what is this value: 5 x10-6?? can you please clear it out?
thank you
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Old 01-09-2014
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Originally Posted by excellence View Post
i understood that Vmax of A =20 so at Km its 20/2= 10,
but i didnt get what is this value: 5 x10-6?? can you please clear it out?
thank you
i found the q on kaplan LN, its clear now, i just got confused due to the no. typing in the post

5x 10-6 represent the conc of the S= Km for enz A, so at 5x10-4 definitely the enz will work at its vmax which is 20 so C is the correct answer.
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