ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The sensitivity of soybean (Glycine max L. Merr, cv. PS47) nodule phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) to inhibition by L-malate in vitro increased when well-nodulated plants were subjected to decapitation (shoot removal). There was no effect of decapitation on the apparent Km of the enzyme for its substrate PEP but the I50 (L-malate) decreased from 4.2 to 1.7 mM. The total amount of PEP doubled and that of malate decreased by half in the nodules of decapitated plants relative to the control plants. This observation was consistent with a decrease in the activity of PEPC in vivo as a result of the increased malate sensitivity of the enzyme observed in vitro. Sucrose levels in the nodules declined in response to decapitation but there were no effects on the levels of glucose, fructose, pyruvate, 2-oxoglutarate, glutamine or glutamate. The results are discussed in terms of the role of protein phosphorylation in the regulation of PEPC activity in legume nodules.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1996.tb00513.x
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