Surviladze Z G, Dudkin S M
Mol Biol (Mosk). 1979 Jan-Feb;13(1):205-15.
Steady state kinetics of DNA depolymerisation in the presence of the DNAase A and Mg2+ ions were investigated at pH 5.5 and wide region of the enzyme, substrate and metal ion concentrations. A model, which is consistent with experimental results obtained is suggested. According to the model catalytically active form of the DNAase A should be a metal-bound enzyme. That species reacts with the metal-free DNA to form the Michaelis complex. The kinetics observed can be described in terms of mechanism which involves covalent enzyme-substrate intermediate formation. It was shown that the second Mg2+ ion binding to the complex Mg2+ DNAase -- DNA (KD - 2.2 . 10(-3) M) enhances the kinetic parameters of the reaction. To rationalise the effect one has to assume that the rate of the intermediate formation was accelerated as a result of the second Mg2+ binding.
在pH 5.5以及酶、底物和金属离子浓度的广泛范围内，研究了在DNA酶A和Mg2+离子存在下DNA解聚的稳态动力学。提出了一个与所获得的实验结果相一致的模型。根据该模型，DNA酶A的催化活性形式应该是一种金属结合酶。该物种与无金属的DNA反应形成米氏复合物。观察到的动力学可以用涉及共价酶-底物中间体形成的机制来描述。结果表明，第二个Mg2+离子与复合物Mg2+-DNA酶-DNA（KD - 2.2.10(-3) M）的结合增强了反应的动力学参数。为了合理解释这种效应，必须假设由于第二个Mg2+的结合，中间体形成的速率加快了。
