ss CARBOXYLATION ENZYMES IN MARINE PHYTOPLANKTON AND ISOLATION AND PURIFICATION OF PYRUVATE CARBOXYLASE FROM AMPHIDINIUM CARTERAE (DINOPHYCEAE)1

Appleby, Geoffrey J.; Colbeck, Jill; Holdsworth, E. S.; Wadman, Hugh

doi:10.1111/j.0022-3646.1980.00290.x

Cited by 12 publications

(15 citation statements)

References 21 publications

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“…The pyruvate carboxylase activity detected in Amphidinium carterae and Gymnodinium sp. (Appleby et al 1980) was confirmed in A. carterae and found in 2 other dinoflagellates species, Amphidinium operculaturn and Scrippsiella trochoidea.…”

Section: Discussionmentioning

confidence: 75%

“…Autotrophic phytoplankton cells mainly assimilate inorganic carbon through the Calvin-Benson cycle via the enzyme ribulose-1,5-bisphosphate carboxylase (Rubisco), but fixation by P-carboxylation [phosphoenolpyruvate carboxylase (PEPC), phosphoenolpyruvate carboxykinase (PEPCK) or pyruvate carboxylase] may be superimposed on this cycle. In diatoms and cyanobacteria, the substrate for P-carboxylation (phos-phoenolpyruvate) originates from 3-phosphoglycerate in light (intermediate of Calvin-Benson cycle), and from a polysaccharide in darkness (Kremer & Berks 1978, Appleby et al 1980, Morris 1980, MortainBertrand et al 1987a, b, 1988a, Owttnm & Colman 1988.…”

Section: Introductionmentioning

confidence: 99%

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Variations in carboxylase activity in marine phytoplankton cultures, ß-carbolxylation in carbon flux studies

Descolas-Gros¹,

Oriol²

1992

Mar. Ecol. Prog. Ser.

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Inorganic carbon may be assimilated through the Calvin-Benson cycle via the enzyme ribulose-1.5-bisphosphate carboxylase (Rubisco) andlor by 0-carboxylation [via the enzymes phosphoenolpyruvate carboxylase (PEPC), phosphoenolpyruvate carboxykinase (PEPCK) or pyruvate carboxylase]. Here, carboxylase activity measurements for marine phytoplankton are described. Two indices measuring carboxylase activity in marine phytoplankton were used. The first measures Rubisco activity per unit chlorophyll [R/Chl; nmol CO2 (pg chl a+b+c)-' h-'] while the second is the ratio of P-carboxylase activity to Rubisco activity, expressed as % (PC/R), which reflects the proportion of inorganic carbon fixed by these 2 groups of carboxylases. These ratios were studied in (1) different algal species in culture, (2) dunng the different growth phases of a culture, and (3) after a light-dark transition to measure the time response of carboxylase activities. These indices were different from one species to another at the same stage of growth. In autotrophic cells, P-carboxylation remained low (PC/R<40). The PCIR ratio increased significantly when R/Chl began to decrease at the end of the growth phase of a culture of Skeletonerna costaturn. The heterotrophic dinoflagellate Crypthecodinjurn cohnii, grown on an organic medium, incorporated inorganic carbon in the dark through PEPCK activity. The wlde range in PC/R ratio observed among the species confirm that in phytoplankton there may exist a continuum between autotrophy and heterotrophy. From a carbon budget point of view the 2 mechanisms are not equivalent. Rubisco fixation uses light as an energy source and results in gross production; 0-carboxylation also fixes inorganic carbon but as energy source uses metabolites synthesized by other pathways in the cell or from the external medium.

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Section: Discussionmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Variations in carboxylase activity in marine phytoplankton cultures, ß-carbolxylation in carbon flux studies

Descolas-Gros¹,

Oriol²

1992

Mar. Ecol. Prog. Ser.

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“…Falkowski & Owens, 1980). Given the very low fi-carboxylase activities measured, incorporation of I4C by fi-carboxylation cannot explain the discrepancy between photosynthesis and Rubisco activity of S. ecornis, as has been suggested for diatoms, flagellates and brown algae (Kremer & Kfippers, 1977;Appleby et al, 1980). Since S. ecornis has a C3 metabolism, high Levels of fl-carboxylation under autotrophic conditions would have been surprising.…”

Section: Discussionmentioning

confidence: 87%

Inadequacy of Rubisco initial and total activities to account for observed rates of photosynthetic carbon dioxide assimilation byScenedesmus ecornis

Mouget

Beeson

Legendre

et al. 1993

European Journal of Phycology

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LOUIS LEGENDRE 3 ANDBoth initial and total activity of ribulose-l,5, bisphosphate carboxylase/oxygenase (Rubisco) measured for the green alga Scenedesmus ecornis are affected by the experimental procedure and they are not sufficiently high to account for the rates of ~4C fixation by photosynthesis. The very low fl-carboxylase activities detected (less than 3% of the Rubisco total activity) cannot explain the difference in CO2 fixation. Attempts to obtain possible optimal conditions (pH, duration of activation with Mg 2+ and HCO3, absence of proteases, linearity of 14C fixation with time) did not lead to increased activity yields. The substrate ribulose-l,5-bisphosphate was found to decrease the initial activity at concentrations higher than 25/IM for algae harvested by centrifugation and having thus experienced several minutes of darkness. Deactivation seems to be primarily responsible for this loss of activity. Furthermore, initial and total activities decrease when the delay before freezing increases, suggesting accumulation of an inhibitor from the light-dark transition metabolism during the first minutes of harvesting.

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“…vivo photosynthesis (e.g. Holdsworth and Bruck 1977;Kremer and Berks 1978;Appleby et al 1980). If such enzymes were active during our experiments, as suggested by our high P,,, : Xase ratios, then the significant differences we observed between the P,,,, : Xase ratios in the 3-and 20-m phytoplankton communities indicate that the contribution of other carboxylases (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…This latter reaction sequence, referred to as "Cd metabolism" in lower plants (Benedict 1978), has been shown to play an important role in the carbon assimilation of marine phytoplankton in both culture and field populations (Beardall et al, 1976;Glover and Morris 1979). Recent work has also indicated that other ,&car-boxylating enzymes may be important in the C, metabolism of certain algae (Holdsworth and Bruck 1977;Appleby et al 1980;Kremer 1981b). It was at first thought that a distinction existed between algal groups with regards to their paths of carbon fixation (Beardall et al 1976) but it now appears that, within a single spccics of alga, the pathway of photosynthetic CO, fixation may vary with changing environmental conditions and with altered physiological states (Mukerji et al 1978).…”

mentioning

confidence: 99%

Carboxylating enzyme activity and photosynthetic end products of phytoplankton in the shallow and deep chlorophyll layers of Castle Lake1

Priscu

Goldman

1983

Limnology & Oceanography

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The patterns of carbon assimilation of the Castle Lake phytoplankton were measured under various environmental conditions. The flow of carbon into polysaccharides and lipids plus low molecular weight metabolites was generally highest at low temperatures and low light (i.e. under-ice and deep-water populations). Enrichment with nitrogen to nitrogen-deficient algae did not significantly alter the patterns of carbon assimilation during time-series experiments. However, the relative rates of polysaccharide and protein synthesis were increased when the entire epilimnion of the lake was fertilized with nitrogen. On the average about 15% more carbon could potentially be fixed by the anaplerotic enzyme phosphoenolpyruvate carboxylase (PEPCase) than the Calvin Cycle enzyme ribulose-l,&bi-phosphate carboxylase (RuBPCase). The parameter, RuBPCase : PEPCase/photon saturated in vivo photosynthesis (I',,,,), was consistently > 1.0 liter.h-l*wg-l C and showed significant differences between the 3-m and 20-m algal populations, indicating that they may be physiologically distinct with respect to carbon metabolism.The proportion of 14C incorporated into protein increased as the ratio of RuBPCase to PEPCase increased. The converse was true for the relative synthesis of lipid + low molecular weight (LMW) compounds while the proportion of 14C incorporated into polysaccharide varied little with RuBPCase : PEPCase. These findings and others from the literature do not corroborate existing simple biochemical models for this relationship, implying that other carboxylating enzymes may be important in the carbon metabolism of certain algae.

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ss CARBOXYLATION ENZYMES IN MARINE PHYTOPLANKTON AND ISOLATION AND PURIFICATION OF PYRUVATE CARBOXYLASE FROM AMPHIDINIUM CARTERAE (DINOPHYCEAE)1

Cited by 12 publications

References 21 publications

Variations in carboxylase activity in marine phytoplankton cultures, ß-carbolxylation in carbon flux studies

Variations in carboxylase activity in marine phytoplankton cultures, ß-carbolxylation in carbon flux studies

Inadequacy of Rubisco initial and total activities to account for observed rates of photosynthetic carbon dioxide assimilation byScenedesmus ecornis

Carboxylating enzyme activity and photosynthetic end products of phytoplankton in the shallow and deep chlorophyll layers of Castle Lake1

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