Protein standard curves: linear regression vs. polynomial fit
Jan van der Lee
baslee at kabelfoon.nl
Mon Aug 24 18:45:11 EST 1998
Wolfgang Schechinger wrote:
> Hi all,
> I noticed that when doing Bradford-sytle protein concentration
> measurements, a 2nd order fit (y=ax^2+bx+c) repeatedly seems to be
> smoother than a linear fit (y=ax+b) for the standard curve.
> Has anybody an explanation for this?
> usual disclaimers apply * This message is RNAse free - please don't touch!
> Wolfgang Schechinger
> University of Tuebingen, Germany
> email: wgschech at med.uni-tuebingen.de * wwWait: http://www.medizin.uni-tuebingen.de/~wgschech/start.htm
The actual fit you should use is y= ax + bxy
or: y= (ax)/(1-bx)
The reason: this reaction is limited in final concentration (starts at 0 and has a maximum eg 2.0 in
l / (example curve)
The curve is only lineair in the lower part.
If you want an/or can use it I could send you a Lotus 1-2-3 spreadsheet with fitting possiblities for all
kinds of curves
Mail me back if you want them.
Regards Jan (holland)
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