FitzGerald P C, Farina R D, Behnke W D
Biochim Biophys Acta. 1983 Feb 28;743(1):43-51. doi: 10.1016/0167-4838(83)90416-8.
The demetallization of various metallo derivatives of Concanavalin A (i.e., MnMnPL, CoMnPL, CaCaPL, CoCaPL and MnCaPL, where PL represents protein in a locked conformation) has been examined by three separate procedures. These include the treatment of the protein with the metal ion chelators, EDTA and terpyridine, and subjecting the protein to low pH (i.e., pH 1.2). In all three procedure and for all five species examined, the immediate product of protein demetallization was the PL conformation previously described by Brown, R.D., III, Brewer, C.F. and Koenig, S.H. (Biochemistry (1977) 16, 3883-3896). The rates of dissociation of the metals from the different protein species, as measured spectrophotometrically using terpyridine, were found to be identical to the rates (k1) of loss of protein sugar binding affinity in the presence of EDTA as measured by assays with the fluorescent sugar, 4-methylumbelliferyl alpha-D-mannoside. The kinetic and thermodynamic data associated with the inactivation of the protein species have allowed the different metallo derivatives to be classed into two general categories. Class I forms include MnMnPL, CoMnPL and CaCaPL and possess an average k1 (25 degrees C) value of 3.88 X 10(-2) s-1 and an average Ea of 14.2 kcal X mol-1. Class II forms CoCaPL and MnCaPL have average values for k1 (25 degrees C) and Ea of 3.67 X 10(-5) s-1 and 21.6 kcal X mol-1, respectively.
已通过三种不同方法研究了伴刀豆球蛋白A的各种金属衍生物（即MnMnPL、CoMnPL、CaCaPL、CoCaPL和MnCaPL，其中PL代表处于锁定构象的蛋白质）的脱金属作用。这些方法包括用金属离子螯合剂乙二胺四乙酸（EDTA）和三联吡啶处理蛋白质，以及使蛋白质处于低pH值（即pH 1.2）环境。在所有这三种方法以及所研究的所有五个种类中，蛋白质脱金属的直接产物是布朗（Brown, R.D., III）、布鲁尔（Brewer, C.F.）和凯尼格（Koenig, S.H.）之前描述过的PL构象（《生物化学》（1977年）第16卷，第3883 - 3896页）。使用三联吡啶通过分光光度法测定，发现不同蛋白质种类中金属解离的速率与在存在EDTA的情况下，用荧光糖4 - 甲基伞形酮基α - D - 甘露糖苷测定的蛋白质糖结合亲和力丧失的速率（k1）相同。与蛋白质种类失活相关的动力学和热力学数据已使不同的金属衍生物分为两大类。I类形式包括MnMnPL、CoMnPL和CaCaPL，其平均k1（25℃）值为3.88×10⁻² s⁻¹，平均活化能为14.2千卡·摩尔⁻¹。II类形式CoCaPL和MnCaPL的k1（25℃）和活化能的平均值分别为3.67×10⁻⁵ s⁻¹和21.6千卡·摩尔⁻¹。
