A study of the in-vitro regulation of phosphoenolpyruvate carboxylase from the epidermis of Commelina communis by malate and glucose-6-phosphate |
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Authors: | Maria E Donkin Joan Taffs E S Martin |
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Institution: | (1) Department of Biological Sciences, Faculty of Science, Plymouth Polytechnic, Drake Circus, Plymouth, Devon, UK |
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Abstract: | Phosphoenolpyruvate (PEP) carboxylase activity in epidermal extracts of Commelina communis has been compared in the presence of malate and glucose-6-phosphate. The activity of PEP carboxylase was inhibited by increasing malate concentrations at several substrate (PEP) concentrations and changes in both the apparent K
m (PEP) and V
max values in the presence of malate suggested the occurence of mixed-type inhibiton. In the presence of glucose-6-phosphate no increase in enzyme activity was observed, although there was a slight decrease in the K
m (PEP). However, glucose-6-phosphate appeared to alleviate the inhibition caused by malate. The possible implications of these properties in the control of malate production in guard cells is discussed.Abbreviations PEP
phosphoenolpyruvate
- Glc6P
glucose-6-phosphate |
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Keywords: | Commelina Epidermis Phosphoenolpyruvate carboxylase Stoma |
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