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giandep
UK
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 Posted - 12/08/2006 : 10:59:27 AM
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Origin Version (Select Help-->About Origin): 7.5
Operating System: winXP
Sorry for my lack of knowledge,
does any body know how to set new non linear curve fitting equation?
I am a biochemist and Im interested in all the different enzymology fittings, like Michaelis and Menten equation (v=(Vmax*s)/(KM+s) s independent variable and v dependent variable), Lineweaver-Burk plot , Eadie-Hofstee plot substrate inhibition and more.
Thankyou for your help.
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larry_lan
China
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Posted - 12/08/2006 : 8:18:55 PM
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Hi:
You can use the Hill function in the Growth/Sigmoidal category. This is a more general form of M-M Function, and you can fix n=1 in your case. I think you can do linear fit to create Lineweaver-Burk plot if you transform v and S to 1/v and 1/S.
To create user-defined fitting function, please read the Origin Help files or This Link.
Larry
OriginLab Technical Services
Edited by - larry_lan on 12/08/2006 8:30:36 PM |
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giandep
UK
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Posted - 12/10/2006 : 8:06:58 PM
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Thank you very much larry for your help.
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peter.cook
UK
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Posted - 01/03/2007 : 2:18:34 PM
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Hi,
I would just like to add thepoint that you should always analyse your enzyme data with non linear regression and any linear plots should not be created by linear regression. You should use the parameters obtained from the non linear regression (eg Michaelis-Menten) to draw the linear.
ie for LineWeaver-Burke y=ax+b
x = 1/S, Y = 1/V, b = 1 / Vmax, a = Km/Vmax
(we use this approach fit to different models, select the best one based on Akaike Information criterion and reisdual plots and then draw linear plots as required ).
Cheers,
pete
Edited by - peter.cook on 01/03/2007 2:47:56 PM |
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Michaelis Menten equation setting