Khalilov R A, Dzhafarova A M, Khizrieva S I
Department of Biochemistry and Biophysics, Dagestan State University, Makhachkala, Republic of Dagestan, Russia.
Bull Exp Biol Med. 2017 Jul;163(3):334-337. doi: 10.1007/s10517-017-3797-8. Epub 2017 Jul 25.
We studied activity and kinetic characteristics of lactate dehydrogenase (LDH) in rat brain under conditions of incomplete global ischemia followed by reperfusion against the background of mild hypothermia. It was found that hypothermia leads to a decrease in LDH activity in the ischemic brain; the maximum velocity of the enzyme-catalyzed activity decreased and Michaelis constant increased, due to which the efficiency of catalysis decreased to the level observed in control rats. Ischemia against the background of hypothermia was accompanied by a decrease in the inhibition constant and narrowing of effective pyruvate concentration range. Blood flow resumption in the ischemic brain against the background of mild hypothermia led to an increase in LDH activity, the maximum reaction velocity increased, and Michaelis constant decreased, which lead to a significant increase in the efficiency of catalysis. This was accompanied by an increase in enzyme inhibition constant and a shift of the optimum on the concentration curve towards lower pyruvate concentrations.
我们研究了在不完全性全脑缺血后再灌注且伴有轻度低温的情况下，大鼠脑内乳酸脱氢酶（LDH）的活性和动力学特征。结果发现，低温导致缺血脑内LDH活性降低；酶催化活性的最大速度下降，米氏常数增加，由此催化效率降至对照大鼠所观察到的水平。低温背景下的缺血伴随着抑制常数降低和有效丙酮酸浓度范围变窄。在轻度低温背景下，缺血脑血流恢复导致LDH活性增加，最大反应速度增加，米氏常数降低，这导致催化效率显著提高。同时，酶抑制常数增加，浓度曲线上的最佳点向较低丙酮酸浓度方向移动。
