[sashikaz]

Hi, I'm having some confusion for my lab report, when I convert my MM graph to a LB graph I get a different value for Vmax and Km when an inhibitor is added and I'm not sure why. I didn't have this problem when analyzing the graphs for the assay solutions without inhibitors. I thought this might just be due to experimental error but according to my TA they are supposed to be different and I have to explain why. The Vmax in the MM plot is estimated 29000microM/min but its 63496 microM/min when solved for in the LB plot. The Km is 0.35 estimates in the MM plot and 1.35 when solved for in the LB plot.If anyone could point me in the right direction I would really appreciate it I'm really stumped here.

*edit: I should have made it clear that I am comparing MM and LB plots for the assays containing inhibitor, not comparing the graphs of an assay without an inhibitor to an assay with an inhibitor

[Babcock_Hall]

Do I assume correctly that these are real data with experimental error, as opposed to imaginary data that have little or no error?  When you found K_m and V_max by the Michaelis-Menten equation, did you eyeball the graph, or did you use nonlinear regression?  Did you use linear regression when you calculated these two parameters from the Lineweaver-Burk? plot

[Babcock_Hall]

A good starting point is to ask yourself whether or not all data points have equal uncertainty.