(a) The experimental concentration data (29 time points) were smoothed and interpolated with a spline function, thereby yielding metabolite levels ofX3at about 300 time points. These X3 values were put into 186 different bins with size 0.03. Among these, 54 bins have at least two X3 values. (b) Graph of X4 values, corresponding to at least two X3 values in each of the X3 bins. Selection of s pairs with a threshold d of 0.3 (here s = 12; see Text) are selected. (c) Pairs in (b) are merged. (d) Resulting functional plot of X4vs. v4; the blue dots represent the dots in (c), while the red triangles represent the true plot of X4vs. v4 in the dynamic model; in reality, these would not be known. (e) Functional plot of X3vs. v3 (blue dots), calculated from the blue dots in (d), and true values of X3 (red triangles) according to the dynamic model. (f) Confirmation that the total mass (represented as the number of 3-carbon units) does not change appreciably over time.
Chou and Voit BMC Systems Biology 2012 6:84 doi:10.1186/1752-0509-6-84