Li Q, Ling J, Liu W Y
Shanghai Institute of Biochemistry, Academiia Sinica, People's Republic of China.
FEBS Lett. 1995 Aug 14;370(1-2):123-6. doi: 10.1016/0014-5793(95)00794-a.
The aldehyde radical of ribose C1' at position 4324 in rat liver 28S rRNA generated by RNA N-glycosidase was either reduced to an hydroxyl group by sodium borohydride or converted into aldimine through a nucleophilic addition of amino acid used as a primary amine. Analysis of the R-fragment of 28S rRNA by polyacrylamide gel electrophoresis showed that the reduction of aldehyde to an hydroxyl group with sodium borohydride was highly specific. The protein synthesis activity of modified ribosomes was partially restored with the removal of the active aldehyde by sodium borohydride or amino acid. Reduction of aldehyde with sodium borohydride restored 43.1% of the protein synthesis activity. Among the twenty natural amino acids tested, tryptophan and histidine could restore 57.4% and 42.1% of the ribosome activity when brome mosaic virus RNA was used as mRNA. We came to the conclusion that the active aldehyde radical at position 4324 of 28S rRNA in modified ribosome may cause the inactivation of the ribosome for protein synthesis.
由RNA N-糖苷酶在大鼠肝脏28S rRNA第4324位上产生的核糖C1'醛基，要么被硼氢化钠还原为羟基，要么通过用作伯胺的氨基酸的亲核加成转化为醛亚胺。通过聚丙烯酰胺凝胶电泳对28S rRNA的R片段进行分析表明，用硼氢化钠将醛还原为羟基具有高度特异性。用硼氢化钠或氨基酸去除活性醛后，修饰核糖体的蛋白质合成活性部分恢复。用硼氢化钠还原醛可恢复43.1%的蛋白质合成活性。在所测试的20种天然氨基酸中，当使用雀麦花叶病毒RNA作为mRNA时，色氨酸和组氨酸可分别恢复57.4%和42.1%的核糖体活性。我们得出结论，修饰核糖体中28S rRNA第4324位上的活性醛基可能导致核糖体失活，从而无法进行蛋白质合成。
