Fig. 3.

The relationship between the growth temperature (T_growth) and the energy of activation (∆H_a) for (A) the Rubisco specificity factor for CO₂/O₂ (S_c/o) in liquid phase, (B) the Rubisco Michaelis–Menten constant for CO₂ (K_c) in liquid phase, and (C) the Rubisco maximum carboxylase turnover rate ($k_{cat}^c$). Each symbol corresponds to individual species (Table 2 for data sources). Open upward triangles, Proteobacteria; open circles, Cyanobacteria; black circles, Bacillariophyta (diatoms); open squares, Chlorophyta (green algae); open diamond, Rhodophyta (red algae); blue squares, C₃ plants from cool habitats; red squares, C₃ plants from warm habitats; green squares C₄ plants. In vitro estimates at discrete temperatures were standardized for study-to-study differences in physico-chemical characteristics for CO₂ and O₂ used as in Figs 1 and 2 and the temperature responses were fitted by Eq. 12. In (A), the data were fitted by a non-linear equation in the form y=−20.911+0.207x–0.009x². In (B) and (C), data fits by linear and different monotonic non-linear equations were statistically not significant (best r² values were 0.090 for (B) and 0.115 for (C), P>0.1 for both).