Saboury Ali Akbar, Ghasemi Setareh, Dahot Mohammad Umar
Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
Indian J Biochem Biophys. 2005 Oct;42(5):326-9.
The interaction of alpha-amylase (from Bacillus amyloliquefaciens) with Mg2+ ion was studied using UV spectrophotometric and isothermal titration calorimetric (ITC) methods at 27 degrees C in 30 mM Tris buffer solution at pH = 7.0. The binding isotherm for metal-protein interaction was easily obtained by carrying out ITC experiment at two different concentrations (2 microM and 50 microM) of the protein. Alpha-Amylase had eight identical and independent binding sites for Mg2+ ion, which showed non-cooperativity in the binding process. The binding of Mg2+ ion was exothermic (deltaH= -17.3 kJ mol(-1)) with association binding constant of 2.08 mM(-1). The binding slightly destabilized the enzyme against thermal denaturation, as evident from absorption studies.
在27摄氏度、pH = 7.0的30 mM Tris缓冲溶液中，使用紫外分光光度法和等温滴定量热法（ITC）研究了（来自解淀粉芽孢杆菌的）α-淀粉酶与Mg2+离子的相互作用。通过在两种不同浓度（2 microM和50 microM）的蛋白质下进行ITC实验，很容易获得金属-蛋白质相互作用的结合等温线。α-淀粉酶对Mg2+离子有八个相同且独立的结合位点，在结合过程中表现出非协同性。Mg2+离子的结合是放热的（ΔH = -17.3 kJ mol(-1)），缔合结合常数为2.08 mM(-1)。从吸收研究可以明显看出，这种结合略微使酶对热变性不稳定。
