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- Title
Glutathione synthetase in tobacco suspension cultures: catalytic properties and localization.
- Authors
Hell, R.; Bergmann, L.
- Abstract
Glutathione synthetase activity (EC 6.3.2.3) was analysed in ammonium Sulfate precipitates of extracts from photoheterotrophically grown cells of Nicotiana tabacum L. cv. Samsun by determination of glutathione as its monobromobimane derivative. Maximal enzyme activity was obtained at pH 8.0-9.0 in Tris-HCl and CHES as buffer systems. The enzyme showed an absolute requirement for Mg2+ and was slightly stimulated by K+. When Mg2+ was replaced by Mn2+ less synthetase activity was observed, and above 30 mM Mn2+ no activity was found. The enzyme was specific for glycine (KM = 0.308 mM). No product formation was observed with β-alanine and γ-aminobutyrate using substrate concentrations of 10 mM. The apparent KM values for γ-glutamylcysteine and γ-glutamyl-L-α-aminobutyrate were, respectively, 0.022 and 0.033 mM. By chloroplast isolation ca 24% of the total glutathione synthetase activity of the cells could be shown to be localized in the chloroplasts, the rest being attributed to the cytoplasm of the tobacco cells.
- Subjects
TOBACCO; GLUTATHIONE; PLANT cell culture; CELL suspensions; CYTOPLASM; CHLOROPLASTS
- Publication
Physiologia Plantarum, 1988, Vol 72, Issue 1, p70
- ISSN
0031-9317
- Publication type
Article
- DOI
10.1111/j.1399-3054.1988.tb06624.x