Optimization of the β factor in the pykF (-) knockout mutant. The model error profile is simulated with respect to the number of integrated enzymes when the β factor is changed as 0.5 (yellow), 1 (red), 2 (black), 4 (green). (a) Mean model error. (b) Relative standard deviation of the model error. The mean for each β is not consistent when the number of incorporated enzymes is zero. This is caused by a non-zero enzyme activity for pykF in the mutant.