Montanaro L, Sperti S, Zamboni M
Ital J Biochem. 1985 Jan-Feb;34(1):1-10.
Gelonin, a single-chain protein which inactivates eukaryotic ribosomes, becomes split into peptides when incubated with SDS. During the chromatographic purification of gelonin on carboxymethylcellulose three overlapping peaks emerge in the gelonin elution region, containing three proteins with small differences in apparent molecular weight (31,500, 30,000 and 29,200). All three proteins are endowed with inhibitory activity on protein synthesis and with proteinase activity, although with different specific activities, and all three give rise to the same peptides upon incubation with SDS, suggesting that they are isoforms of gelonin. The gelonin-associated proteinase acts only on gelonin, while it is inactive on the most common substrates for endoproteinases. The proteolytic activity is not inhibited by inhibitors of serine- or SH-proteinases, while it is completely abolished by chelating agents. Divalent cations restore the proteolytic activity inhibited by EDTA. The stability of the proteinase activity on exposure of gelonin to extreme values of pH or to prolonged incubation has been investigated. The inhibitory activity on protein synthesis and the proteinase activity are differently affected by these treatments.
去糖链蓖麻毒素是一种使真核生物核糖体失活的单链蛋白质，与十二烷基硫酸钠（SDS）一起孵育时会分解成肽段。在羧甲基纤维素上对去糖链蓖麻毒素进行色谱纯化过程中，在去糖链蓖麻毒素洗脱区域出现三个重叠峰，包含三种表观分子量略有差异的蛋白质（31,500、30,000和29,200）。这三种蛋白质均具有蛋白质合成抑制活性和蛋白酶活性，尽管比活性不同，并且与SDS孵育时均产生相同的肽段，表明它们是去糖链蓖麻毒素的同工型。与去糖链蓖麻毒素相关的蛋白酶仅作用于去糖链蓖麻毒素，而对最常见的内蛋白酶底物无活性。蛋白水解活性不受丝氨酸蛋白酶或巯基蛋白酶抑制剂的抑制，而螯合剂可使其完全丧失活性。二价阳离子可恢复被乙二胺四乙酸（EDTA）抑制的蛋白水解活性。研究了去糖链蓖麻毒素在暴露于极端pH值或长时间孵育时蛋白酶活性的稳定性。这些处理对蛋白质合成抑制活性和蛋白酶活性的影响不同。
