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Topic: Best Kinetic Plots, plus Kcat?  (Read 6233 times)

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Offline YULivin4

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Best Kinetic Plots, plus Kcat?
« on: April 30, 2008, 07:05:45 PM »
I'm working on my final lab report for the year and we are asked to plot enzyme kinetics using 4 different plot types.

Michaelis-menten
Lineweaver-burk
Eadie-Hofstee
Hanes-wolf

For these plots we need to determine which is the one that gives the best data.  Now I feel that michaelis-menten is the best and am working on the explanation.  I feel that the lineweaver-burk has flaws in that you need to extrapolate the data far back to the y-axis giving the 1/Vmax some variance depending on the fit of the line.  Also the fact that the largest values are actually the lowest readings, this puts a lot of dependence on the accuracy of the spectrophotometer used.  As for the other two, most of the people i talk to can't give me any insight about those.  Most haven't heard of them (like me never heard of it till this lab).  So I someone could shed some light on these types of plots.  Pros/Cons?, thanks.

Also we need to evaluate the Kcat from our Vmax and Km...I can find info about how to solve it but I need to have "prism 5", which i don't have or even know what it is.  So if someone can give me a simple equation or something I can derive it from would be very appreciated. 

I just want to be done with this.  I do love a teacher that wants you to report on an item that you have never learned about.  Thanks in advance for you help

YU

Offline Yggdrasil

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Re: Best Kinetic Plots, plus Kcat?
« Reply #1 on: April 30, 2008, 08:49:31 PM »
The first issue you should consider is what your curve will look like on each graph.  When you plot your data, do you get a line or a curve?  How easy is it to fit your data to the shape of the curve (i.e. can you do it by hand or do you need special software?).  Do the plots give you any additional information about factors that could be effecting the kinetics (e.g. cooperativity)?  Is it easy to distinguish the effects of inhibitors using each of the plots?

Your discussion of the Lineweaver-burk plot is excellent, however.

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