Terech A, Pucheault J, Ferradini C
Biochem Biophys Res Commun. 1983 May 31;113(1):114-20. doi: 10.1016/0006-291x(83)90439-4.
A pulse radiolysis study of the Mn-superoxide dismutase from Paracoccus denitrificans has shown that, at concentration of 0(2)-. below 0.8 x 10(-4)M, the catalyzed dismutation of 0(2)-. is a first order reaction with regard to 0(2)-.. At concentration of 0(2)-. above 0.8 x 10(-4)M, the Mn-superoxide dismutase is shown to catalyze superoxide dismutation with a mechanism which exhibits saturation kinetics. This behavior was previously found in the bovine Cu/Zn-superoxide dismutase and in the Fe-superoxide dismutase from Photobacterium leiognathi. Two parameters of catalysis were determined from pH 5 to pH 11: the rate constant k was pH independent at basic pH. The variation of Km with pH indicated that the enzyme possessed an ionizable group with pK 9.8 which participates to the substrate binding.
对反硝化副球菌的锰超氧化物歧化酶进行的脉冲辐解研究表明，在超氧阴离子浓度低于0.8×10⁻⁴M时，该酶催化的超氧阴离子歧化反应对超氧阴离子而言是一级反应。在超氧阴离子浓度高于0.8×10⁻⁴M时，锰超氧化物歧化酶催化超氧阴离子歧化反应的机制呈现出饱和动力学。这种行为先前在牛的铜/锌超氧化物歧化酶以及鱼发光杆菌的铁超氧化物歧化酶中也有发现。在pH值从5到11的范围内测定了两个催化参数：速率常数k在碱性pH条件下与pH无关。Km随pH的变化表明该酶具有一个pK为9.8的可电离基团，它参与底物结合。
