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Carbonic anhydrase activity and inorganic carbon fluxes in low‐ and high‐C 1 cells of Chlamydomonas reinhardtü and Scenedesmus obliquus
Author(s) -
Palmqvist Kristin,
Yu JianWei,
Badger Murray R.
Publication year - 1994
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1994.tb08812.x
Subject(s) - chlamydomonas reinhardtii , scenedesmus obliquus , carbonic anhydrase , periplasmic space , total inorganic carbon , cyanobacteria , photosynthesis , algae , extracellular , chlamydomonas , biochemistry , intracellular , chemistry , rubisco , biology , biophysics , botany , carbon dioxide , enzyme , mutant , genetics , organic chemistry , escherichia coli , bacteria , gene
Carbonic anhydrase (CA) activity associated with high‐ and low‐dissolved inorganic carbon (C 1 ) grown cells was examined in whole cells by measuring 18 O exchange from doubly labeled CO 2 ( 13 C 18 O 18 O). Both algal species showed the presence of extracellular (periplasmic) as well as intracellular CA activity, which were both greatly increased in low‐C 1 cells. The periplasmic CA activity was at least 40‐fold higher in lowcompared to high‐C 1 cells in both C. reinhardtii and S. obliquus . while low‐C 1 cells of S. obliquus showed the highest activity of internal CA. The CA inhibitor ethoxyzolamide showed a strong inhibition of the C 1 uptake process in both C. reinhardtii and S. obliquus as in cyanobacteria. which may indicate that the nature of the primary uptake process is similar in both green algae and cyanobacteria. By using a mass spectrometnc disequilibrium technique it was possible to separate the C 1 fluxes of net HCO − 3 ‐uptake and net CO 2 ‐uptake during steady‐state photosynthesis in high‐ and Sow‐C 1 grown cells of Chlamydomonas reinhardtii (WT. 2137+) and Scenedesmus obliquus (WT. D3). It was found that both high‐ and low‐C 1 cells of the two algae can utilize both CO 2 and HCO − 3 for photosynthesis, although low‐C 1 cells have a higher affinity for the uptake of both C 1 species. Induction at low‐C 1 causes an increase in the affinity of both species for HCO − 3 and CO 2 ; changes in net CO 2 ‐uptake were, however, significantly greater.