at 20˚C ~50µM: at 0˚C ~15 µM
||Kranz SA, Young JN, Hopkinson BM, Goldman JA, Tortell PD, Morel FM. Low temperature reduces the energetic requirement for the CO2 concentrating mechanism in diatoms. New Phytol. 2015 Jan205(1):192-201. doi: 10.1111/nph.12976 p.198 left column 3rd paragraphPubMed ID25308897
||Young JN, Goldman JA, Kranz SA, Tortell PD, Morel FM. Slow carboxylation of Rubisco constrains the rate of carbon fixation during Antarctic phytoplankton blooms. New Phytol. 2015 Jan205(1):172-81. doi: 10.1111/nph.13021PubMed ID25283055
||P.198 left column 3rd paragraph: "Low temperatures affect several physical, chemical and biochemical processes that are important to the functioning of a CCM [carbon concentrating mechanism] in psychrophilic phytoplankton: the CO2 solubility in seawater increases from c. 13 μM at 20°C to c. 25 μM at 0°C at equilibrium with the atmosphere, the diffusion coefficient of dissolved CO2 decreases (by a factor of 2 between 20 and 0°C (Boudreau, 1997)), the affinity of enzymes for their substrate changes (e.g. the KC of diatom Rubisco decreases from c. 50 μM at 20°C to c. 15 μM at 0°C (primary source)), and the turnover rate of most enzymes decrease (e.g. by a factor of 10 for Rubisco between 20 and 0°C (primary source)), although some cold‐adapted enzymes maintain relatively high kinetics (as is apparently the case for carbonic anhydrase in the diatoms in the WAP [Western Antarctic Peninsula])."