13C-NMR study of CO2-fixation during the heterotrophic growth in Chlorobium thiosulfatophilum |
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Authors: | Toomas Paalme Abira Olivson Raivo Vilu |
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Affiliation: | Institute of Chemical Physics and Biophysics of Estonian Academy of Sciences, Tallinn 200 001 USSR |
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Abstract: | The functioning of the biosynthetic pathways of the amino acids alanine, glycine, aspartic acid, glutamic acid and tyrosine, and of nucleosides in the photosynthetic bacterium Chlorobium thiosulfatophilum during heterotrophic growth on 13CO2 and unlabelled acetate was investigated using 13C-NMR as the method for determination of the labelling patterns of the separated substances. On the basis of the analysis of the multiplet structure of the spectra of the tightly-coupled systems, the conclusion was drawn that the Calvin cycle does not function in the experimental conditions used. The labelling pattern of the glutamic acid indicated that about 30% of the amino acid molecules were synthesized through the reactions of the reductive carboxylic acid cycle, the remaining 70% being derived from oxaloacetate and exogenous acetate through the reactions of the Krebs cycle. Labelling patterns of the nucleosides were in agreement with their known biosynthetic pathways. |
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Keywords: | Heterotrophic growth (Chl. thiosulfatophilum) |
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