Activities of ribulose-1,5-bisphosphate carboxylase and glutamine synthetase in isolated mesophyll cells exposed to tabtoxin

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Ribulose-1,5-bisphosphate carboxylase activity was unaltered in isolated cells of Nicoliana tabacum and Asparagus sprengeri exposed to concentrations of tabtoxin that inhibited glutamine synthetase and photosynthesis, Although it has been reported that a purified preparation of ribulose-1,5-bisphosphate carboxylase was inactivated by tabtoxin, the experiments described here indicate that the enzyme in living cells is not affected. Photosynthesis was reduced in cells exposed to tabtoxin but was associated with the increase in intercellular ammonia, which occurs when glutamine synthetase is inhibited. The results support the hypothesis that the inhibition of glutamine synthetase is the single primary biochemical lesion that leads to symptoms in tissues exposed to tabtoxin.
Original languageEnglish
Pages (from-to)59-68
Number of pages10
JournalPhysiological and Molecular Plant Pathology
Issue number1
Publication statusPublished - Jul 1986

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