Spencer M, Binns M M
J Chromatogr. 1982 Apr 23;238(2):297-306. doi: 10.1016/s0021-9673(00)81315-1.
E. coli tRNA was fractionated by the application of ammonium sulphate reverse gradients to Sepharose 4B. Variations in elution profile were partly attributable to differences between batches of Sepharose. The profile also varied with column length and gradient parameters. This suggests the existence of two distinct mechanisms which do not separate different tRNAs in the same sequence. The first mechanisms, believed to be interfacial precipitation, releases tRNAs progressively as the salt concentration is reduced. A second mechanism introduces adsorptive retardation in which molecules lag behind the solvent. This process, widely believed not to be important in the chromatography of macromolecules with multiple binding sites, is in the present case mainly responsible for the improved resolution of peaks on passage down a long column. Isocratic (constant-salt) fractionation is also feasible. The Sepharose batch variation affects the second mechanism more than the first.
通过对琼脂糖4B应用硫酸铵反向梯度对大肠杆菌转运RNA进行分级分离。洗脱图谱的变化部分归因于不同批次琼脂糖之间的差异。该图谱也随柱长和梯度参数而变化。这表明存在两种不同的机制，它们不会以相同顺序分离不同的转运RNA。第一种机制被认为是界面沉淀，随着盐浓度降低，转运RNA会逐渐释放。第二种机制引入了吸附阻滞，其中分子滞后于溶剂。人们普遍认为，在具有多个结合位点的大分子色谱中，这一过程并不重要，但在本案例中，它主要负责在长柱中向下流动时峰分辨率的提高。等度（恒盐）分级分离也是可行的。琼脂糖批次的变化对第二种机制的影响大于对第一种机制的影响。
