Heat-stable and fructose 1,6-bisphosphate-activated L-lactate dehydrogenase from an extremely thermophilic bacterium.
Heat-stable L-lactate dehydrogenase [EC 1.1.1.27] was purified from an extremely thermophilic bacterium belonging to the genus Thermus, and it showed an allosteric nature dependent on fructose 1,6-bisphosphate as an effector. The enzyme had a molecular weight of approximately 120,000 with a subunit molecular weight of 31,000. For pyruvate reduction, the optimal pH was found to be 4.5. At neutral pH, which is a more physiological region, little enzyme activity was observed, but marked reaction resulted from the addition of fructose 1,6-bisphosphate. This addition stabilized the enzyme toward heat treatment at up to 95 degrees C. The optimal temperature for the enzyme reaction was approximately 80 degrees C for pyruvate reduction and 95 degrees C for lactate oxidation.
D004789:Enzyme Activation / Q000187:drug effects; D005635:Fructosediphosphates / Q000494:pharmacology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007770:L-Lactate Dehydrogenase / Q000302:isolation & purification*; D008970:Molecular Weight; D011489:Protein Denaturation; D013824:Thermus / Q000201:enzymology*
D005635:Fructosediphosphates; D007770:L-Lactate Dehydrogenase; C029063:fructose-1,6-diphosphate