SUBSTRATE ACTIVATION AND PRODUCT INHIBITION OF LDH ACTIVITY IN HUMAN SKELETAL-MUSCLE
SUBSTRATE ACTIVATION AND PRODUCT INHIBITION OF LDH ACTIVITY IN HUMAN SKELETAL-MUSCLE
复制标题
DOI：
10.1111/j.1748-1716.1974.tb05719.x
复制
发表时间：
1974-01-01
期刊：
影响因子：
--
通讯作者：
SJODIN, B
中科院分区：
文献类型：
--
作者：
KARLSSON, J;HULTEN, B;SJODIN, B
底物激活和产物抑制对人骨骼肌LDH活性的双向影响进行了研究。丙酮酸和乳酸的正向和反向反应Km分别为0.8 × 10 - 4和0.9 × 10 - 2 M。随着NAD和NADH浓度的增加，LDH活性呈曲线性增加，但不能获得Km值。对于乳酸浓度等于0.3 × 10 - 2 M的正向反应，获得了对应于50% Vmax的LDH活性抑制，对于反向反应（丙酮酸盐），相应值为1.0 × 10 - 4 M。乳酸和丙酮酸的浓度大致对应于运动时骨骼肌中观察到的最大值，两个方向的LDH活性抑制等于或大于Vmax的70%。它的结论是，在anin vitrosystem浓度的乳酸盐和丙酮酸盐的生理条件下观察到在人体骨骼肌将诱导一个显着的产品抑制LDH活性从人体骨骼肌在两个反应方向。这似乎是合理的假设，目前的体外研究结果可能反映了功能运作在一个原位。因此，LDH催化反应的产物（乳酸或丙酮酸）可能对人骨骼肌中的无氧糖酵解以及乳酸的氧化具有调节作用。
Substrate activation and product inhibition have been studied on LDH activity in both directions in human skeletal muscle. Kmfor the forward and backward reactions for pyruvate and lactate were found to be 0.8 × 10‐4and 0.9 times 10‐2M, respectively. For increases in concentrations of NAD and NADH the LDH activity was found to increase curvilinearly and no Kmvalue could be obtained. Inhibition of the LDH activity corresponding to 50 % of Vmaxwas obtained for the forward reaction with a lactate concentration equal to 0.3 × 10‐2M and for the backward reaction (pyruvate) the corresponding value was 1.0 X10‐4M. With concentrations of lactate and pyruvate approximately corresponding to maximal values observed in skeletal muscle with exercise, the inhibition of LDH activity in both directions was equal to or more than 70 % of Vmax. It is concluded that in anin vitrosystem concentrations of lactate and pyruvate similar to what are observed under physiological conditions in human skeletal muscles will induce a significant product inhibition on LDH activity obtained from human skeletal muscles in both reaction directions. It seems reasonable to assume that the presentin vitrofindings might reflect functions operating in anin situsystem. Thus it is possible that the products of the LDH catalysed reactions (lactate or pyruvate) might have a regulatory effect on the anaerobic glycolysis as well as the oxidation of lactate in human skeletal muscle.