Thermodynamic Properties of Muscle Lactate Dehydrogenase from Misgurnus fossilis Fish, Adapted to Different Temperatures

Adaptation of loach Misgurnus fossilis for 25 days to low (5oC) and relatively high (18oC) temperatures changed the thermodynamic properties of lactate dehydrogenase (LDH) from skeletal muscle, as revealed by differential scanning microcalorimetry. The enzyme purified from fish adapted to low temperature had greater heat capacity. The denaturation temperature was the same for both LDH forms. The denaturation enthalpy for the enzyme from fish adapted to high temperature was greater than for the enzyme from fish adapted to low temperature. The number of thermodynamic cooperative units (the ratio ∆ H d/∆ H d eff ) was about two for both LDH forms.