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Thermodynamics of fundamental body-relevant bioreactions


The aim of this project is to provide reliable thermodynamic data on body-relevant reactions like ATP-ADP or NADH-NAD+. For this project, reaction and phase equilibria at different conditions (reactant concentration, temperature, presence of additives or buffer) will be measured and modeled.



The Gibbs energy of reaction determines the concentration of the reactants and products in the equilibrium state. For several body-relevant bioreactions, published Gibbs energy of reaction data diverges strongly (e.g. for the ATP hydrolysis, values between -30 and -40 kJ/mol are published). This is caused by the fact that many authors neglect several important influence factors (e.g. temperature, pH, buffer system, any non-idealities of the system due to van der Waals interactions and hydrogen bonding, the size of the molecules etc.). Not accounting for these conditions strongly falsifies the results drawn from raw-measurement data. It is of highest importance to reduce the uncertainty as well as the inconsistencies in Gibbs energy of reaction values to a minimum extent. This requires reliable thermodynamic basic data as well as thermodynamic models accounting for the most important physiological conditions (i.e. intracellular pH, concentration of Mg, other salts, and polyelectrolytes). In a first work at the Laboratory of Thermodynamics, TU Dortmund, it was shown how system conditions influence the Gibbs energy of reaction values at the example of two reactions (G6P-F6P and methyl ferulate hydrolysis). With this knowledge, it is now possible to apply the available tools to are highly relevant bioreactions. The aim of this project is to provide reliable thermodynamic data on reactions like ATP-ADP or NADH-NAD+. The influence of system conditions on the reaction equilibria shall be investigated. In a second step, this procedure will be adopted to consecutive equilibrium reactions where the single reactions are part of. Also in such cases, exact Gibbs energy of reaction values are crucial for a proper understanding of the reaction. In order to achieve these objectives, measurements and modeling approaches will be required. First, equilibrium concentrations will be measured depending on initial reactant concentration in order to obtain the experimental thermodynamic equilibrium constant Ka. Second, the activity coefficients for the components that take part in the reaction will be measured. These data will be used for the prediction of reaction equilibria. Finally, the predicted and the experimental K values will be compared and the influence of additives or temperature on Gibbs energy of reaction values will be investigated. The availability of thermodynamic consistent and reliable data will give new insight into understanding biological single-step and multi-step reactions depending on the system conditions.



Foto von PD Dr.-Ing. Christoph Held

PD Dr.-Ing. Christoph Held


TU Dortmund
Fakultät Bio- und Chemieingenieurwesen
Emil-Figge-Str. 70
44227 Dortmund

Raum G2-513