Figure 5.

Focal correlations of previous analyses are not robust to new data. Points with black outlines are from ref (6), and dashed gray lines represent the best fit to FI Rubisco data. Histograms for k_cat,C, S_C/O, and K_C are plotted on parallel axes. Panel A plots k_cat,C against S_C/O. k_cat,C and S_C/O correlate with an R of approximately −0.6 among FI Rubiscos as compared to ≈0.9 previously.^5,6 The 95% confidence intervals are (−4.0, −2.0) for the fit exponent and (3 × 10⁴, 2 × 10⁸) for the prefactor (slope and intercept on a log–log scale, respectively), indicating that the form of k_cat,C–S_C/O correlation is very uncertain. Notably, S_C/O displays very limited variation overall and especially within physiological groupings with sufficient data. Median S_C/O values are 177 for red algae (σ* = 1.2; N = 6), 98 for C₃ plants (σ* = 1.1; N = 162), 80 for C₄ plants (σ* = 1.1; N = 35), and 48 for cyanobacteria (σ* = 1.1; N = 16). Panel B plots k_cat,C against K_C. Here, the R is ≈0.5 as compared to ≈0.9 previously.⁶ This fit is more robust, with 95% confidence intervals of (0.3, 0.5) and (0.8, 1.5) for the fit exponent and prefactor, respectively.