ENVIRONMENTAL-TEMPERATURE AFFECTS THE STR UCTURAL AND FUNCTIONAL-PROPERTIES OF LACTATE-DEHYDROGENASE FROM FISH SKELETAL-MUSCLES

Adaptation of fishes to low and high environmental temperatures gives rise to certain changes in kinetic and structural properties of LDH fr om skeletal muscles. The K(M) versus temperature plot for pyruvate of the enzyme isolated from fishes adapted to low temperatures has a mini mum at low measurement temperatures, whereas adaptation to high temper atures leads to the enzyme showing a minimum at high temperatures. The LDH isolated from fishes adapted to low environmental temperatures is more stable relative to both thermal and urea-induced inactivation. T he differences in the kinetic properties of the enzymes from fishes ad apted to low and high temperatures disappear after treatment with urea and subsequent reactivation.