Higgins R C, Gottlieb L D
Biochem Genet. 1984 Oct;22(9-10):957-79. doi: 10.1007/BF00499485.
We examined structural and functional properties of the recently duplicated cytosolic isozymes of phosphoglucose isomerase (PGI) (EC 5.3.1.9) of the wild plant Clarkia xantiana and related species. A new purification protocol yielded PGIs with high specific activities. The duplicated PGI isozymes showed similar substrate affinities (apparent Km) in both catalytic directions. A newly devised competitive enzyme-linked immunosorbent assay (ELISA), using polyclonal antibodies, distinguished sodium dodecyl sulfate (SDS)-denatured PGIs coded by the duplicated loci but did not discriminate between allelic products of one of the loci. In vitro dissociation and reassociation experiments revealed that the duplicated subunits differed in their efficiency of reassociation. The difference was closely correlated with differences between the isozymes in their in vivo accumulation. In contrast, allelic subunits in species with or without the duplication were able to reassociate with similar efficiency. The duplicated PGI isozymes have diverged more in structural properties than kinetic ones. The total evidence suggests that mechanisms have evolved which reduce the potential consequences of the duplication.
我们研究了野生植物黄花克拉花及其相关物种中最近复制的磷酸葡萄糖异构酶（PGI）（EC 5.3.1.9）胞质同工酶的结构和功能特性。一种新的纯化方案得到了具有高比活性的PGI。复制的PGI同工酶在两个催化方向上表现出相似的底物亲和力（表观Km）。一种新设计的使用多克隆抗体的竞争性酶联免疫吸附测定（ELISA），能够区分由复制基因座编码的十二烷基硫酸钠（SDS）变性的PGI，但无法区分其中一个基因座的等位基因产物。体外解离和重新结合实验表明，复制的亚基在重新结合效率上存在差异。这种差异与同工酶在体内积累的差异密切相关。相比之下，有或没有复制的物种中的等位基因亚基能够以相似的效率重新结合。复制的PGI同工酶在结构特性上的差异比动力学特性上的差异更大。总的证据表明，已经进化出了一些机制来减少复制的潜在后果。
