Thermodynamic buffering, stable non-equilibrium and establishment of the computable structure of plant metabolism

Publication date: Available online 13 November 2018Source: Progress in Biophysics and Molecular BiologyAuthor(s): Abir U. Igamberdiev, Leszek A. KleczkowskiAbstractThe equilibria of coenzyme nucleotides and substrates established in plant cells generate simple rules that govern the plant metabolome and provide optimal conditions for the non-equilibrium fluxes of major metabolic processes such as ATP synthesis, CO2 fixation, and mitochondrial respiration. Fast and abundant enzymes, such as adenylate kinase, carbonic anhydrase or malate dehydrogenase, provide constant substrate flux for these processes. These “buffering” enzymes follow the Michaelis-Menten (MM) kinetics and operate near equilibrium. The non-equilibrium “engine” enzymes, such as ATP synthase, Rubisco or the respiratory complexes, follow the modified version of MM kinetics due to their high concentration and low concentration of their substrates. The equilibrium reactions serve as control gates for the non-equilibrium flux through the engine enzymes establishing the balance of the fluxes of load and consumption of metabolic components. Under the coordinated operation of buffering and engine enzymes, the concentrations of free and Mg-bound adenylates and of free Mg2+ are set, serving as feedback signals from the adenylate metabolome. Those are linked to various cell energetics parameters, including membrane potentials. Also, internal levels of reduced and oxidized pyridine nucleotides are established in th...
Source: Progress in Biophysics and Molecular Biology - Category: Molecular Biology Source Type: research