Ribulose-1,5-bisphosphate carboxylase/oxygenase from thermophilic red algae with a strong specificity for CO2 fixation.
Strongly carboxylase-specific ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) was found in Galdieria partita and Cyanidium caldarium (Cyanidiophyceae). The relative specificity, VcKo/VoKc, of Galdieria and Cyanidium RuBisCO was 238 and 222, respectively; 2.4 to 2.5-fold that of higher plant RuBisCOs. The apparent Km of RuBisCO from the thermophilic red algae for CO2 was 6 to 7 microM and the smallest of the values reported so far for other RuBisCOs. The pre-rhodophyte Porphiridium purpureum, which lives at moderate temperatures, had RuBisCO with the relative specificity value of 144. A large difference (5.2 kcal x mol(-1)) in the activation energies between the carboxylase and oxygenase activities in Galdieria RuBisCO was a cause of the strong specificity for the carboxylase activity.
Uemura
K
K
Plant Molecular Physiology Laboratory, Research Institute of Innovative Technology for the Earth (RITE), Kizu, Kyoto, Japan.
Anwaruzzaman
Miyachi
S
S
Yokota
A
A
D002245:Carbon Dioxide / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D000461:Rhodophyta / Q000201:enzymology*; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism*; D013379:Substrate Specificity
D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase