Arakawa T, Yphantis D A
J Biol Chem. 1987 Jun 5;262(16):7484-5.
Recombinant DNA-derived human tumor necrosis factor-alpha from Escherichia coli was examined by equilibrium ultracentrifugation under conditions similar to those where gel filtration experiments suggested an oligomeric structure. Short-column equilibrium experiments at concentrations in the range 0.015-0.12% at pH 8.5 in 0.04 M Tris/Tris-HCl gave molecular weights corresponding to 3 times the sequence molecular weight both in the presence and absence of 0.1 M NaCl. Long (2.6 mm)-column experiments under the same solvent conditions indicated molecular weights of 51,900 +/- 900 in the absence of added NaCl and 52,600 +/- 700 in the presence of added 0.1 M NaCl. No evidence of any species other than the trimer was found.
在与凝胶过滤实验表明存在寡聚结构的条件相似的情况下，通过平衡超速离心法对源自大肠杆菌的重组DNA衍生的人肿瘤坏死因子-α进行了检测。在0.04 M Tris/Tris-HCl中，pH值为8.5，浓度范围为0.015 - 0.12%的短柱平衡实验表明，无论有无0.1 M NaCl，分子量均相当于序列分子量的3倍。在相同溶剂条件下的长（2.6 mm）柱实验表明，在未添加NaCl时分子量为51,900 ± 900，在添加0.1 M NaCl时分子量为52,600 ± 700。未发现除三聚体以外的任何其他物种的证据。
