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Study of Lactate Dehydrogenase Kinetics in Trehalose Solutions. Temperature Effect

Some organisms may adapt to extreme environmental conditions such as drought, high salinity, freezing or high temperature. The accumulation of compatible solutes in bacteria, yeast and plants is a metabolic response to heat‐shock and osmotic stress. Namely, compatible solutes are those molecules which at high concentrations does not interfere with structure or function of enzymes. Trehalose has been considered so long as a compatible solute, which has showed protective/stabilizing properties in structure and function of membranes and enzymes. Studies have demonstrated that trehalose displays the highest efficiency in protecting enzyme activity under dehydration and heat shock. However, there are few reports on the effect of trehalose in enzyme kinetic parameters. In this work, the effect of physiological concentration of trehalose on enzyme kinetics of lactate dehydrogenase (LDH) type II from rabbit muscle was studied. LDH kinetics was assayed in absence and presence of different concentrations of trehalose (0.2 to 0.8M) and at different temperatures (25‐35 °C). The results showed that trehalose affects the kinetic parameters Km and Vmax, and the activation energy (Ea) for LDH reaction. Interestingly, trehalose effect increased with concentration. In contrast, the raise in temperature lead to slightly relieve LDH from such effects. Kinetic parameters Vmax and Km decreased as trehalose concentration was increased. Therefore, trehalose presence lead to diminish the maximum rate of catalysis while increasing affinity for substrate in LDH. Notably, the amount of energy required to overpass the transition state was increased by trehalose.