Sherry A D, Newman A D, Gutz C G
Biochemistry. 1975 May 20;14(10):2191-6. doi: 10.1021/bi00681a023.
Divalent cadmium and lead and the trivalent lanthanides bind in the trasition metal site (S1) of concamavanlin A and induce saccharide binding to the protein in the presence of calcium. Partial activation of the protein in the presence of lanthanides alone indicates these ions bind into both transition metal (S1) and calcium sites (S2). The activity of a lanthanide-protein derivative may be increased by the addition of either calcium or a transition metal ion. The saccharide binding activity decreases in the order Zn2+ is greater than Ni2+ is greater than Co2+ is greater than Mn2+ is greater than Cd2+ reflecting the order of binding constants for these ions in the transition metal site. Like the lanthanides, divalent cadmium substitutes for both the transition metal ion and calcium ion to partially activate the protein. Divalent lead substitutes only for the transition metal ion and partially activates the protein upon addingcalcium. The data are consistent with a model in which saccharide binding activity is independent of the metal size in S1 but critically dependent upon metal size in S2.
二价镉和铅以及三价镧系元素结合在伴刀豆球蛋白A的过渡金属位点（S1），并在有钙存在的情况下诱导糖类与蛋白质结合。仅在镧系元素存在时蛋白质的部分活化表明这些离子同时结合到过渡金属（S1）和钙位点（S2）。通过添加钙或过渡金属离子，镧系元素 - 蛋白质衍生物的活性可能会增加。糖类结合活性按Zn2+＞Ni2+＞Co2+＞Mn2+＞Cd2+的顺序降低，这反映了这些离子在过渡金属位点的结合常数顺序。与镧系元素一样，二价镉替代过渡金属离子和钙离子以部分活化蛋白质。二价铅仅替代过渡金属离子，并在添加钙时部分活化蛋白质。这些数据与一个模型一致，在该模型中，糖类结合活性与S1中的金属大小无关，但关键取决于S2中的金属大小。
