Holtet T L, Nielsen K L, Etzerodt M, Moestrup S K, Gliemann J, Sottrup-Jensen L, Thøgersen H C
Department of Chemistry, University of Arhus, Denmark.
FEBS Lett. 1994 May 16;344(2-3):242-6. doi: 10.1016/0014-5793(94)00349-1.
A recombinant version of the receptor binding domain (RBDv) of human alpha 2-macroglobulin (alpha 2M) has been expressed in E. coli and refolded using a novel iterative procedure. RBDv (Val1299-Ala1451) is extended by 15 residues at the N-terminal side of the Lys1313-Glu papain cleavage site in human alpha 2M. RBDv contains the intra-chain bridge Cys1329-Cys1444 and is soluble and monomeric. Competition experiments with 125I-labelled methylamine-treated alpha 2M reveal that RBDv binds to the placental receptor for transformed alpha 2M with a Kd of 8 nM, i.e. the binding affinity of RBDv is of the same order of magnitude as the intrinsic affinity for binding of one domain in transformed alpha 2M to one receptor molecule.
人α2-巨球蛋白（α2M）受体结合域的重组版本（RBDv）已在大肠杆菌中表达，并使用一种新颖的迭代程序进行重折叠。RBDv（Val1299-Ala1451）在人α2M中Lys1313-Glu木瓜蛋白酶切割位点的N端一侧延伸了15个残基。RBDv包含链内桥Cys1329-Cys1444，并且是可溶的单体。用125I标记的甲胺处理的α2M进行的竞争实验表明，RBDv以8 nM的Kd值与转化型α2M的胎盘受体结合，即RBDv的结合亲和力与转化型α2M中一个结构域与一个受体分子结合的固有亲和力处于同一数量级。
