[Thermal stability of lactate dehydrogenase and alcohol dehydrogenase incorporated into highly concentrated gels].
The rate constants for inactivation of lactate dehydrogenase and alcohol dehydrogenase in solution at 65 degrees C (pH 7,5) are 0,72 and 0,013 min-1, respectively. The enzyme incorporation into acrylamide gels results in immobilized enzymes, whose residual activity is 18--25% of the original one. In 6,7% gels the rate of thermal inactivation for lactate dehydrogenase is decreased nearly 10-fold, whereas the inactivation rate for alcohol dehydrogenase is increased 4,6-fold as compared to the soluble enzymes. In 14% and 40% gels the inactivation constants for lactate dehydrogenase are 6,3.10(-3) and 5,9.10(-4) min-1, respectively. In 60% gels the thermal inactivation of lactate dehydrogenase is decelerated 3600-fold as compared to the native enzyme. The enthalpy and enthropy for the inactivation of the native enzyme are equal to 62,8 kcal/mole and 116,9 cal/(mole.grad.) for the native enzyme and those of gel-incorporated (6,7%) enzyme -- 38,7 kcal/mole and 42 cal/(mole.grad.), respectively. The thermal stability of alcohol dehydrogenase in 60% gels is increased 12-fold. To prevent gel swelling, methacrylic acid and allylamine were added to the matrix, with subsequent treatment by dicyclohexylcarbodiimide. The enzyme activity of the modified gels is 2,7--3% of that for the 6,7% gels. The stability of lactate dehydrogenase in such gels is significantly increased. A mechanism of stabilization of the subunit enzymes in highly concentrated gels is discussed.
D000178:Acrylamides; D000429:Alcohol Oxidoreductases / Q000378:metabolism; D002151:Calorimetry; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D004355:Drug Stability; D004800:Enzymes, Immobilized / Q000378:metabolism; D005782:Gels; D006358:Hot Temperature; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D013816:Thermodynamics
D000178:Acrylamides; D004800:Enzymes, Immobilized; D005782:Gels; D004024:Dicyclohexylcarbodiimide; D000429:Alcohol Oxidoreductases; D007770:L-Lactate Dehydrogenase
Termicheskaia stabil'nost laktatdegidrogenazy i alkogol'degidrogenazy, vkliuchennykh v vysokokontsentrirovannye geli.