scholarly journals Partitioning of Nitrogen among Ribulose-1,5-bisphosphate Carboxylase/Oxygenase, Phosphoenolpyruvate Carboxylase, and Pyruvate Orthophosphate Dikinase as Related to Biomass Productivity in Maize Seedlings

1984 ◽  
Vol 75 (3) ◽  
pp. 665-669 ◽  
Author(s):  
Tatsuo Sugiyama ◽  
Masuhiko Mizuno ◽  
Masanori Hayashi
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Biomass Productivity ◽  
Maize Seedlings ◽  
Bisphosphate Carboxylase ◽  
Pyruvate Orthophosphate Dikinase ◽  
Orthophosphate Dikinase

Phosphoenolpyruvate carboxylase mediated carbon flow in a cyanobacterium

1988 ◽  
Vol 66 (2) ◽  
pp. 93-99 ◽  
Author(s):  
George W. Owttrim ◽  
Brian Colman
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Protein Production ◽  
Carbon Fixation ◽  
Fixed Carbon ◽  
Free System ◽  
Pyruvate Orthophosphate Dikinase ◽  
Orthophosphate Dikinase ◽  
Phosphoglyceric Acid ◽  
A Cell

The source of the substrate phosphoenolpyruvate (PEP) for phosphoenolpyruvate carboxylase (PEP-case) activity in the cyanobacterium Coccochloris peniocystis has been investigated, as well as possible sinks for this carbon. PEP was not produced by pyruvate orthophosphate dikinase, as this activity was not detectable in cell-free lysates. PEP is supplied from photosynthetically or glycolytically produced 3-phosphoglyceric acid (3-PGA), as carbon was observed to flow from 3-PGA to C4 acids in a cell-free system. This indicates PEP-case activity is dependent on photosynthetically fixed carbon and thus two separate carbon fixation reactions occur in the cell in the light. Estimates of the in vivo concentrations of various metabolites indicates that neither substrate nor inhibitor concentrations limit enzyme activity in vivo. Thus PEP-case activity in vivo appears to be limited by the supply of PEP and is, therefore, high in the light and low in the dark. The nitrogen storage product cyanophycin was identified as one sink for carbon fixed by PEP-case. As a culture aged, cyanophycin production increased, while chlorophyll and protein production decreased.

Effects of Water Stress on Carbon Exchange Rate and Activities of Photosynthetic Enzymes in Leaves of Sugarcane (Saccharum Sp.)

1996 ◽  
Vol 23 (6) ◽  
pp. 719 ◽  
Author(s):  
YC Du ◽  
Y Kawamitsu ◽  
A Nose ◽  
S Hiyane ◽  
S Murayama ◽  
...  
Keyword(s):  
Exchange Rate ◽  
Water Stress ◽  
Stomatal Closure ◽  
Total Soluble Protein ◽  
Carbon Exchange ◽  
Bisphosphate Carboxylase ◽  
Pyruvate Orthophosphate Dikinase ◽  
Photosynthetic Enzymes ◽  
Orthophosphate Dikinase ◽  
Saccharum Sp

The responses of carbon exchange rate (CER), stomatal conductance (gs), activities of phosphoenolpyruvate carboxylase (PEPcase), NADP malic enzyme (NADP-ME), ribulose-1,5- bisphosphate carboxylase (Rubisco), fructose-1,6-bisphosphatase (FBPase) and pyruvate, orthophosphate dikinase (PPDK), and contents of chlorophyll (Chl) and total soluble protein (Tsp) in leaves of sugar cane (Saccharum sp. cv. NiF4) to gradually developed water stress were investigated. The initial inhibitions of CER, gs, activities of the photosynthetic enzymes and contents of Chl and Tsp were observed from leaf water potentials (Ψw) of -0.37 MPa. During water stress, CER and gs, decreased in a non-linear way, activities of the five enzymes and contents of Chl and Tsp decreased linearly with decreasing leaf Ψw. The changes of gs the photosynthetic enzymes, Chl and Tsp were highly related to the changes of CER. The decline in CER during water stress was caused by both stomatal and non- stomatal limitations. Above leaf �w of -0.85 MPa, the decline in CER was caused by stomatal closure, below -0.85 MPa, the decline in CER was caused by non-stornatal limitation. Among non-stomatal components, PPDK activities decreased 9.1 times during water stress, much more than other enzymes which decreased from 2 to 4 times. Measured PPDK activities were only a little higher than the corresponding CER values at various leaf Ψw suggesting that PPDK is very likely to be the limiting enzyme to photosynthesis under water stress.

scholarly journals Changes in Abundance of Enzymes Involved in Organic Acid, Amino Acid and Sugar Metabolism, and Photosynthesis during the Ripening of Blackberry Fruit

2009 ◽  
Vol 134 (2) ◽  
pp. 167-175 ◽  
Author(s):  
Franco Famiani ◽  
Robert P. Walker
Keyword(s):  
Amino Acid ◽  
Gel Electrophoresis ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Sugar Metabolism ◽  
Large Decrease ◽  
Bisphosphate Carboxylase ◽  
Pyruvate Orthophosphate Dikinase ◽  
Orthophosphate Dikinase

Although information is available regarding the content of various metabolites such as sugars and organic/amino acids in blackberry (Rubus L.), little is known about its enzyme composition. The aim of this study was to investigate changes in the abundance of various enzymes during the ripening of blackberry. Blackberry is an aggregate fruit, composed of a receptacle and several drupelets attached to it, which in turn, are composed of the flesh (mesocarp plus epicarp) and seed enclosed in the endocarp; therefore, these parts were analyzed separately along with the pedicel. The enzymes studied participate in organic/amino acid and sugar metabolism and photosynthesis, processes known to be important in fruit development. These enzymes were phosphoenolpyruvate carboxykinase [PEPCK (EC:4.1.1.49)], phosphoenolpyruvate carboxylase [PEPC (EC:4.1.1.31)], pyruvate, orthophosphate dikinase [PPDK (EC:2.7.9.1)], cytosolic aspartate aminotransferase [cyt AspAT (EC:2.6.1.1)], aldolase (EC:4.1.2.13), glutamine synthetase [GS (EC:6.3.1.2)], and ribulose-1,5-bisphosphate carboxylase/oxygenase [RUBISCO (EC:4.1.1.39)]. To avoid problems in measuring enzyme activity, the approach taken was to use antibodies specific for each enzyme in conjunction with immunoblotting of sodium dodecyl sulfate polyacrylamide gel electrophoresis. During ripening, there were marked changes in abundance of several of these enzymes and these changes were dependent on the tissue investigated. PEPCK appeared when organic acids decreased in the flesh and was only detected in this tissue, whereas PPDK was not detected in any tissue. In the flesh, there was a large decrease in abundance of RUBISCO, plastidic GS, and plastidic aldolase, but little change in cytosolic GS, cytosolic aldolase, and PEPC. In seeds, there was a decrease in the abundance of all enzymes. In the receptacle and pedicel, apart from a large decrease in RUBISCO in the receptacle, there was little change in enzyme abundance.

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