scholarly journals Impacts of Rhizosphere CO₂ on Root Phosphoenolpyruvate Carboxylase Activity, Root Respiration Rate and Rhizodeposition in Populus spp.

2000 ◽  
Author(s):  
Dawn Matarese
Keyword(s):  
Respiration Rate ◽  
Phosphoenolpyruvate Carboxylase ◽  
Root Respiration ◽  
Carboxylase Activity ◽  
Populus Spp

scholarly journals Relationship between NH+4 Assimilation Rate and in Vivo Phosphoenolpyruvate Carboxylase Activity

1990 ◽  
Vol 94 (1) ◽  
pp. 284-290 ◽  
Author(s):  
Greg C. Vanlerberghe ◽  
Kathryn A. Schuller ◽  
Ronald G. Smith ◽  
Regina Feil ◽  
William C. Plaxton ◽  
...  
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Assimilation Rate ◽  
Carboxylase Activity

scholarly journals A study of stabilization of gluconeogenic activity in rat liver slices by calcium and manganese ions

1972 ◽  
Vol 129 (2) ◽  
pp. 231-239 ◽  
Author(s):  
Anne Roobol ◽  
G. A. O. Alleyne
Keyword(s):  
Rat Liver ◽  
Phosphoenolpyruvate Carboxylase ◽  
Incubation Medium ◽  
Lysosomal Enzymes ◽  
Glucose Production ◽  
Liver Slice ◽  
Manganese Ions ◽  
Slice Preparation ◽  
Carboxylase Activity ◽  
Bivalent Cations

1. The effect of some bivalent cations on gluconeogenesis by the rat liver-slice preparation has been investigated. 2. Ca2+and Mn2+stimulated glucose production from a range of substrates but not from glycerol. Mg2+had no effect on the rate of glucose production. 3. Ca2+were required to maintain phosphoenolpyruvate carboxylase activity in the slice preparation. 4. Ca2+and Mn2+, but not Mg2+, retarded the release of lysosomal enzymes from the slice into the incubation medium. 5. It is proposed that Ca2+and Mn2+stimulate glucose production by stabilizing the lysosome system in the liver-slice preparation. 6. The value of the liver-slice preparation as a means of measuring hepatic gluconeogenesis is discussed.

Activation and Inactivation of Phosphoenolpyruvate Carboxylase in Leaf Extracts From C4 Species

1978 ◽  
Vol 5 (5) ◽  
pp. 571 ◽  
Author(s):  
MD Hatch ◽  
IR Oliver
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Phosphoenolpyruvate Carboxylase ◽  
Bovine Serum ◽  
Leaf Extracts ◽  
Small Molecular Weight ◽  
Carboxylase Activity ◽  
C4 Species ◽  
The Stability

The stability of phosphoenolpyruvate carboxylase (EC 4.1.1.31) was examined following extraction of the enzyme from leaves of several C4 plants. Extracts were rapidly processed on small Sephadex G-25 columns to free protein of small-molecular-weight compounds. With most of the species examined, activity was rapidly lost at both 0 and 25°C when the pH was about 7.8 or higher. Addition of bovine serum albumin to extracts incubated at 25°C and pH 8.2 not only prevented inactivation with several species, but resulted in a substantial increase in activity. The addition of dithiothreitol plus Mg2+ to extracts from some of these species reduced or prevented inactivation. With extracts maintained at 0°C, addition of either bovine serum albumin or dithiothreitol was effective only in reducing the rate of inactivation in extracts. Phosphoenolpyruvate carboxylase activity remained stable, or increased substantially, when extracts buffered between pH 7.4 and 6.9 were incubated at either 0 or 25°C. Activation was usually complete within an hour and was often significantly greater at 25°C or when bovine serum albumin was added. The activity of partially purified phosphoenolpyruvate carboxylase from Zea mays was similarly affected by pH, temperature, and bovine serum albumin. The present studies raise doubts about the accuracy of phosphoenolpyruvate carboxylase determinations made during the course of some previous studies on C4 species. Reliable procedures for the determination of phosphoenolpyruvate carboxylase activity in C4 plant extracts are described. Possible physiological implications of the results are considered.

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