Pangburn M K
Department of Biochemistry, University of Texas Health Science Center, Tyler 75710.
FEBS Lett. 1992 Aug 24;308(3):280-2. doi: 10.1016/0014-5793(92)81293-u.
Purified alpha 2-macroglobulin and complement proteins C3 and C4 were treated with ammonia to break their intramolecular thioester bonds and reform the original free cysteinyl and glutamyl side chains. When this reaction was performed at low temperature a conformational intermediate was trapped which lacked a thioester, but which could refold to the native structure and spontaneously reform the thioester and full biological function. The findings suggest that these proteins may undergo spontaneous post-translational self-modification forming the thioesters without involvement of enzymes or high energy metabolites such as ATP.
纯化的α2-巨球蛋白以及补体蛋白C3和C4用氨处理，以断裂其分子内硫酯键，并使原来的游离半胱氨酰和谷氨酰侧链重新形成。当此反应在低温下进行时，捕获到一种构象中间体，其缺乏硫酯，但能重新折叠成天然结构，并自发地重新形成硫酯和完全的生物学功能。这些发现表明，这些蛋白质可能在没有酶或ATP等高能量代谢物参与的情况下，经历自发的翻译后自我修饰形成硫酯。
