Mathematical Modelling of the Influence of Different Concentrations of Oxaloacetate to Glycerol-3-Phosphate Dehydrogenase Structure

The study was devoted to the influence of different concentrations of oxaloacetate on the conformational structure of glycerol-3-phosphate dehydrogenase in a temperature gradient, using differential scanning fluorimetry on a Prometheus NT.48 device (NanoTemper Technologies, Germany). We studied the fluorescence ratio (350/330 nm) of glycerol-3-phosphate dehydrogenase in the presence of oxaloacetate at concentrations of 0.5–16 µM in a temperature gradient of 20–95 °C. We built linear regression models for the physiological temperature range and nonlinear models (polynomial of the third degree) for the temperature range corresponding to protein melting. Temperature was the independent variable; fluorescence ratio was the variable. The effect of different oxaloacetate concentrations on glycerol-3-phosphate dehydrogenase thermostability was evaluated by comparing the parameters of obtained regression models. At the physiological temperature range of 20–40 °C, the fluorescence ratios and their growth rates at oxaloacetate concentrations of 0.5-8 µM (p < 0.001) were found to be lower than those of controls. Higher average fluorescence ratios and growth rates were detected at oxaloacetate concentrations of 16 µM (p < 0.001). When heating over 45 °C, no differences were found in the average denaturation temperature of glycerol-3-phosphate dehydrogenase between the oxaloacetate concentrations studied. The experiment demonstrates the change in the total amplitude of the fluorescence signal in the process of heating the enzyme. The effect of biologically active compounds on fluorescence ratio differs in the area of low concentrations (0.5 and 1 µM) and high concentrations (16 µM). Oxaloacetate at a final concentration of 0.5–1 µM contributes to the thermodynamic stability of glycerol-3-phosphate dehydrogenase, while the concentration of 16 µM causes a decrease in its thermostability.