Decarboxylation of primary and end products of photosynthesis at different oxygen concentrations
| العنوان: | Decarboxylation of primary and end products of photosynthesis at different oxygen concentrations |
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| المؤلفون: | Olav Keerberg, Tiit Pärnik |
| المصدر: | Journal of Experimental Botany. 46:1439-1477 |
| بيانات النشر: | Oxford University Press (OUP), 1995. |
| سنة النشر: | 1995 |
| مصطلحات موضوعية: | Primary (chemistry), chemistry, Biochemistry, Physiology, Decarboxylation, Environmental chemistry, chemistry.chemical_element, Plant Science, Photosynthesis, Oxygen |
| الوصف: | A radiogasometric method for the determination of the rates of intracellular decarboxylation of primary and end products of steady-state photosynthesis in the light has been worked out. On the basis of oxygen dependence of the CO2 evolution, two types of decarboxylation, oxygenase (photorespiration) and oxidase (dark respiration), have been distinguished. Oxygenase decarboxylation is linearly dependent on O2 concentration in the range from 0 to 210 mmol mol−1, which is characteristic of the oxygenation of RuBP, the ratelimiting reaction of the glycolate cycle. Oxidase decarboxylation is saturated at relatively low O2 concentration (of about 15 mmol mol−1), similar to the oxidative reactions associated with glycolysis and the Krebs cycle. In the C3 plants (tobacco, wheat, barley) we have studied, primary products were decarb-oxylated predominantly via the oxygenase mechanism; the oxidase component was 3–15% of the total rate of the decarboxylation of primary photosynthates in the light. The oxygenase mechanism was also involved in the decarboxylation of end products of photosynthesis. The rate of this component exceeded by 3 to 5 times the rate of oxidase decarboxylation of end products in the light. It has been suggested that compounds derived from the degradation of end products of photosynthesis are incorporated into the reductive pentose phosphate cycle and, via the cycle, into the glycolate cycle where they are decarboxylated. In this way, four components of plant leaf respiration in the light may be distinguished according to the substrates and mechanisms of decarboxylation. In the dark, only one of them, oxidase decarboxylation of end products, is functioning. The rate of this component has been shown to be partially suppressed by light. |
| تدمد: | 1460-2431 0022-0957 |
| DOI: | 10.1093/jxb/46.special_issue.1439 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_________::b1cde5d87c501f37d86456d33d9396eb https://doi.org/10.1093/jxb/46.special_issue.1439 |
| رقم الانضمام: | edsair.doi...........b1cde5d87c501f37d86456d33d9396eb |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 14602431 00220957 |
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| DOI: | 10.1093/jxb/46.special_issue.1439 |