Chadha K C, Sclair M, Sulkowski E, Carter W A
Biochemistry. 1978 Jan 10;17(1):196-200. doi: 10.1021/bi00594a029.
Molecular sieving of human leukocyte interferon revealed an apparent molecular weight of 26,000. However, after denaturation by guanidine hydrochloride in the presence of a reducing agent and reactivation by extensive dialysis, a molecular weight of only 21,000 was observed. The reactivated human leukocyte interferon (mol wt 21,000) gave a single peak of activity when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, confirming that a single molecular weight species was generated by the denaturation and reactivation procedure. A partial unfolding of the molecule was evident when the interferon preparation was heated to 50 degrees C in the absence or presence of an unfolding agent and then sieved on Sephadex G-100 Superfine. These results suggest that the interferon molecule undergoes a proteolytic cleavage probably by a protease present in extracellular fluid. Thus, a peptide fragment dissociates from the parent molecule when human leukocyte interferon is denatured in the presence of a reducing agent, resulting in a drop of 5,000 in molecular weight; interestingly, the resultant 21,000 molecular weight form still retains its antiviral activity.
人白细胞干扰素的分子筛分析显示其表观分子量为26,000。然而，在还原剂存在的情况下用盐酸胍变性并通过广泛透析重新激活后，观察到分子量仅为21,000。当通过十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳分析时，重新激活的人白细胞干扰素（分子量21,000）呈现出单一的活性峰，证实变性和重新激活过程产生了单一分子量的物种。当干扰素制剂在不存在或存在变性剂的情况下加热至50℃，然后在Sephadex G - 100 Superfine上进行筛分，分子的部分解折叠是明显的。这些结果表明，干扰素分子可能被细胞外液中存在的蛋白酶进行蛋白水解切割。因此，当人白细胞干扰素在还原剂存在下变性时，一个肽片段从母体分子上解离，导致分子量下降5,000；有趣的是，所得的分子量为21,000的形式仍保留其抗病毒活性。
