THERMODYNAMIC PROPERTIES OF LACTATE-DEHYD ROGENASE FROM MUSCLES OF FISHES ADAPTED TO DIFFERENT ENVIRONMENTAL TEMPERATURES

Adaptation of leach Misgurnus fossilis during 25 days to low (5 degree s C) and relatively high (18 degrees C) temperatures leads to change o f the thermodynamic properties of lactate dehydrogenase (LDH) from ske letal muscles. Differential scanning microcalorimetry has been used to study the thermodynamic properties of this enzyme. The enzyme purifie d from fish adapted to low temperature has a greater value of heat cap acity (C-p). The temperature of denaturation (T-d) was the same for th e both LDH forms. The enthalpy of the denaturation (Delta h(d)) of enz yme purified from fish adapted to high temperature was greater than on e of enzyme from fish adapted to low temperature. The number of thermo dynamic cooperative units (the ratio Delta H-d(cal)/Delta H-d(eff)) wa s about two for the both LDH forms.