scholarly journals Light Adaptation/Acclimation of Photosynthesis and the Regulation of Ribulose-1,5-Bisphosphate Carboxylase Activity in Sun and Shade Plants

1989 ◽  
Vol 91 (1) ◽  
pp. 379-386 ◽  
Author(s):  
Jeffrey R. Seemann
Keyword(s):  
Light Adaptation ◽  
Carboxylase Activity ◽  
Bisphosphate Carboxylase ◽  
Sun And Shade ◽  
Shade Plants

Role of salicylic acid in regulation of cadmium toxicity in wheat ( Triticum aestivum L.)

2009 ◽  
Vol 57 (3) ◽  
pp. 321-333 ◽  
Author(s):  
H. Moussa ◽  
S. EL-Gamal
Keyword(s):  
Pyruvate Carboxylase ◽  
Cadmium Toxicity ◽  
Triticum Aestivum L ◽  
Carboxylase Activity ◽  
Bisphosphate Carboxylase ◽  
Cd Accumulation ◽  
Phosphoenol Pyruvate ◽  
Relative Water ◽  
Aba Content

Treatment with CdCl 2 (0, 100, 400 and 1000 μM) resulted in the inhibition of root dry biomass and root elongation and to increased Cd accumulation in the roots. These treatments also decreased the relative water content, chlorophyll content, 14 CO fixation, phosphoenol pyruvate carboxylase and ribulose-1,5-bisphosphate carboxylase activity and abscisic acid (ABA) content, while increasing the malondialdehyde, hydrogen peroxide and free proline contents and causing changes in the chloroplast and root ultrastructure. Pretreatment of seeds with SA (500 μM) for 20 h resulted in the amelioration of these effects.

scholarly journals Ribulose 1,5-bisphosphate carboxylase. Effect on the catalytic properties of changing methionine-330 to leucine in the Rhodospirillum rubrum enzyme

1986 ◽  
Vol 235 (3) ◽  
pp. 839-846 ◽  
Author(s):  
B E Terzaghi ◽  
W A Laing ◽  
J T Christeller ◽  
G B Petersen ◽  
D F Hill
Keyword(s):  
Rhodospirillum Rubrum ◽  
Oligonucleotide Primer ◽  
Similar Amount ◽  
Ribulose Bisphosphate Carboxylase ◽  
Ribulose Bisphosphate ◽  
Carboxylase Activity ◽  
Bisphosphate Carboxylase ◽  
Ribulose Bisphosphate Carboxylase Oxygenase ◽  
In The Wild ◽  
The Stability

Oligonucleotide-directed mutagenesis of cloned Rhodospirillum rubrum ribulose bisphosphate carboxylase/oxygenase with a synthetic 13mer oligonucleotide primer was used to effect a change at Met-330 to Leu-330. The resultant enzyme was kinetically examined in some detail and the following changes were found. The Km(CO2) increased from 0.16 to 2.35 mM, the Km(ribulose bisphosphate) increased from 0.05 to 1.40 mM for the carboxylase reaction and by a similar amount for the oxygenase reaction. The Ki(O2) increased from 0.17 to 6.00 mM, but the ratio of carboxylase activity to oxygenase activity was scarcely affected by the change in amino acid. The binding of the transition state analogue 2-carboxyribitol 1,5-bisphosphate was reversible in the mutant and essentially irreversible in the wild type enzyme. Inhibition by fructose bisphosphate, competitive with ribulose bisphosphate, was slightly increased in the mutant enzyme. These data suggest that the change of the residue from methionine to leucine decreases the stability of the enediol reaction intermediate.

scholarly journals Ribulose bisphosphate carboxylase/oxygenase in toluene-permeabilized Rhodospirillum rubrum

1983 ◽  
Vol 212 (1) ◽  
pp. 45-54 ◽  
Author(s):  
I Storrø ◽  
B A McFadden
Keyword(s):  
Rhodospirillum Rubrum ◽  
Decay Rates ◽  
Dual Function ◽  
Co2 Removal ◽  
Ribulose Bisphosphate Carboxylase ◽  
Ribulose Bisphosphate ◽  
Carboxylase Activity ◽  
Bisphosphate Carboxylase ◽  
Ribulose Bisphosphate Carboxylase Oxygenase ◽  
The Stability

Toluene-permeabilized Rhodospirillum rubrum cells were used to study activation of and catalysis by the dual-function enzyme ribulose bisphosphate carboxylase/oxygenase. Incubation with CO2 provided as HCO3-, followed by rapid removal of CO2 at 2 degrees C and subsequent incubation at 30 degrees C before assay, enabled a determination of decay rates of the carboxylase and the oxygenase. Half-times at 30 degrees C with 20 mM-Mg2+ were 10.8 and 3.7 min respectively. Additionally, the concentrations of CO2 required for half-maximal activation were 56 and 72 microM for the oxygenase and the carboxylase respectively. After activation and CO2 removal, inactivation of ribulose bisphosphate oxygenase in the presence of 1 mM- or 20mM-Mn2+ was slower than that with the same concentrations of Co2+ or Mg2+. Only the addition of Mg2+ supported ribulose bisphosphate carboxylase activity, as Mn2+, Co2+ and Ni2+ had no effect. A pH increase after activation in the range 6.8-8.0 decreased the stability of the carboxylase but in the range 7.2-8.0 increased the stability of the oxygenase. With regard to catalysis. Km values for ribulose 1,5-bisphosphate4- were 1.5 and 67 microM for the oxygenase and the carboxylase respectively, and 125 microM for O2. Over a broad range of CO2 concentrations in the activation mixture, the pH optima were 7.8 and 8-9.2 for the carboxylase and the oxygenase respectively. The ratio of specific activities was constant (9:1 for the carboxylase/oxygenase) of ribulose bisphosphate carboxylase/oxygenase in toluene-treated Rsp. rubrum. Below concentrations of 10 microM-CO2 in the activation mixture, this ratio increased.

Photosynthetic Enzyme Activities in the C3-C4 Intermediate Neurachne minor S. T . Blake (Poaceae)

1986 ◽  
Vol 13 (3) ◽  
pp. 399 ◽  
Author(s):  
PW Hattersley ◽  
NE Stone
Keyword(s):  
Malic Enzyme ◽  
Acid Decarboxylase ◽  
Decarboxylase Activity ◽  
Carboxylase Activity ◽  
Pep Carboxylase ◽  
C3 Plant ◽  
Bisphosphate Carboxylase ◽  
C3 Species ◽  
Species Activity ◽  
Pep Carboxykinase

The activities of eight key photosynthetic enzymes were measured in leaf blade extracts of the C3-C4 intermediate Neurachne minor S. T. Blake, its C3 and C4 relatives, C3-C4 Panicum milioides Nees ex Trin., and controls (all Poaceae). Phosphoenolpyruvate (PEP) carboxylase (PEPC) activity in N. minor (5.46 �mol mg Chl-1 min-1) is higher than previously reported for any other C3-C3 plant, and the ratio of ribulose-1,5-bisphosphate carboxylase activity to PEPC activity is lower than for P. milioides or C3 species. Activity of pyruvate,PI dikinase (up to 0.88 �mol mg Chl-1 min-1) is 3-5 times higher than in P. milioides. Assays of NADP-malic enzyme (NADP-ME), NAD-malic enzyme (NAD-ME) and PEP carboxykinase (PCK) show Paraneurachne muelleri (Hack.) S. T. Blake and Neurachne munroi (F. Muell.) F. Muell., N. minor's two close C4 relatives, to be NADP-ME type, as predicted from leaf anatomy. Aspartate and alanine aminotransferase activities in these species are higher than expected, however. N. minor (C3-C4) exhibits higher C4 acid decarboxylase activity than C3 species or P. milioides, for NADP-ME only (up to 1.07 �mol mg Chl-1 min-1). Our results suggest that N. minor possesses a limited C4 acid cycle, and that it is the most C4-like C3-C4 intermediate grass currently identified, comparable with some of the known C3-C4 Flaveria (Asteraceae) species.

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