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21 Φεβ 2018 · The present chapter summarizes available data on plant respiratory fractionation, and presents a critical discussion about the metabolic origin of its variation, in the light of recent developments in understanding the compartmentation and plasticity of plant respiration.
Isotopic fractionation differs between C4 carbon fixation and C3, due to the spatial separation in C4 plants of CO 2 capture (in the mesophyll cells) and the Calvin cycle (in the bundle sheath cells). In C4 plants, carbon is converted to bicarbonate, fixed into oxaloacetate via the enzyme phosphoenolpyruvate (PEP) carboxylase, and is then ...
During photosynthetic CO2 fixation fractionation of stable carbon isotopes occurs and, consequently, plants are generally depleted in the heavier isotope 13C. Carbon isotope discrimination (Δ) is a measure of this process and depends on fractionation during...
Here, we focus on metabolic 12C/13C fractionations that provide the key to understanding d13C in plant metabo-lites. A consistent body of data on enzymatic isotope frac-tionations and d13C in (or within) metabolites is now available and is essential for interpreting isotopic signals.
The data of figure 1 show that many steps in the carbon cycle are accompanied by isotope fractionation. One of the most important processes in nature which causes fractionation of carbon is photosynthetic car-bon assimilation by green plants. Both terrestrial and marine plants have lower C1./C12 ratios than their
1 Ιαν 1981 · Our models for isotope fractionation in plants are based on the cumulative fractionations associated with various individual steps (such as stomatal diffusion, C02-HCO3 equilibration, carboxylation, etc.).
n isotope discrimination during photosynthesis. In this chapter, the fundamental chemical, physical and biochemical principles of carb. n isotope fractionation in plants are reviewed. The effects of fractionation processes occurring during photo-synthesis and during carbon metabo.
