A radiotracer probe to study metal interaction with human lactate dehydrogenase isoenzymes.
A radiotracer probe to study metal interaction with human lactate dehydrogenase isoenzymes.
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用于研究金属与人乳酸脱氢酶同工酶相互作用的放射性示踪剂探针。
DOI：
10.1007/bf01024900
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Wright,CE
中科院分区：
文献类型：
--
作者：
Menon,MP;Wright,CE
亲电银离子完全破坏乳酸脱氢酶同工酶LDH-1的活性，而其他过渡金属离子则不同程度地降低其活性。用110mAg标记的银离子标记的放射性示踪探针研究了LDH的变性机理，并测定了底物与酶结合的活性部位数。纯化的LDH-1与110mAg标记的银离子反应，混合物通过Sephadex G-75-120凝胶分离可能在反应过程中形成的110mAg-LDH络合物。由此得到的洗脱曲线显示形成了稳定的络合物。根据110mAg结合的LDH的总放射性，计算了标记的Ag+的比活度和所用的LDH的量，即Ag+与1摩尔的LDH反应的摩尔数之比。这被发现约为4.0，这表明在LDH中有四个结合位点，可能每个亚基上一个。有银离子和无银离子时乳酸脱氢酶催化L-P反应的动力学研究表明，银离子参与了竞争抑制，且相互作用符合“锁和钥匙”模型。其他金属对催化的抑制作用可能是非竞争性的。
The electrophilic Ag+ion was found to destroy completely the enzymatic activity of lactate dehydrogenase isoenzyme LDH-1 while other transition metal ions reduced its activity in varying degrees. A radiotracer probe involving110mAg-labeled silver ion was used to understand the mechanism of denaturation of LDH and also to determine the number of active sites, if any, for substrate binding with the enzyme. Purified LDH-1 was reacted with110mAg-labeled silver ion and the mixture was passed through the sephadex G-75-120 gel to separate the110mAg-LDH complex that might be formed during the reaction. The resulting elution curve revealed that a stable complex was formed. From the total radioactivity of110mAg bound LDH, the specific activity of labeled Ag+and the amount of LDH used the ratio of the number of moles of Ag+reacted with 1 mol of LDH was computed. This was found to be approximately 4.0, indicating that there are four binding sites in LDH, probably one on each subunit. Kinetic studies of LDH catalysis of L-P reaction in the presence and absence of Ag+ion suggest that silver ion is involved in competitive inhibition and that the interaction conforms to the “lock-and-key” model. The inhibition of catalysis by other metals is presumably of a noncompetitive type.