HYPUSINE IN EIF-4D--BIOSYNTHESIS AND FUNCTION

真核蛋白翻译起始因子5A（eIF-5A）含有一个 这似乎是唯一的细胞蛋白质与此 独特的氨基酸 羟腐胺赖氨酸是通过转移后产生的 将多胺亚精胺的丁胺部分转化为赖氨酸残基 在eIF-5A前体中形成脱氧羟腐胺赖氨酸，然后羟基化 形成羟腐胺赖氨酸 这些发现揭示了一种新的细胞代谢 通路 羟腐胺赖氨酸是eIF-5A在大肠杆菌中的生物活性所必需的。 体外翻译起始测定和羟腐胺赖氨酸和eIF-5A出现 是真核细胞生长的重要元素。 因此，羟腐胺赖氨酸 生物合成步骤、脱氧羟腐胺赖氨酸合成和脱氧羟腐胺赖氨酸 羟基化提供了特殊潜在干预目标， 细胞增殖 几种脱氧羟腐胺赖氨酸酶的抑制剂 合成酶，和脱氧羟腐胺赖氨酸羟化酶的开发和它们的细胞 效果已经过检验。 最有效的脱氧羟腐胺赖氨酸抑制剂 合成酶单胍基-1，7-二氨基庚烷，（Ki=0.01微摩尔，与 亚精胺的Km值为4 μ mol）时， CHO细胞中羟腐胺赖氨酸形成和生长抑制剂（IC 50 生长抑制0.3微摩尔）。 该化合物被以下物质积极吸收： 多胺运输系统。 多胺缺陷的突变CHO细胞 转运对单胍基-1，7- 二氨基庚烷，表明其发挥抗增殖活性 通过抑制羟腐胺赖氨酸合成而在细胞内释放。 胍基化 二胺代表一类新的抗增殖剂，其作用 其中一种靶向于一种特定的细胞过程， 生物合成

Eukaryotic protein translation iniation factor 5A (eIF-5A) contains one residue of hypusine and appears to be the only cellular protein with this unique amino acid. Hypusine is produced post-translationally by transfer of the butylamine portion of the polyamine spermidine to a lysine residue in the eIF-5A precursor to form deoxyhypusine followed by hydroxylation to form hypusine. These findings reveal a novel cellular metabolic pathway. Hypusine is essential for the biological activity of eIF-5A in an in vitro translation initiation assay and hypusine and eIF-5A appear to be vital elements for growth of eukaryotic cells. Thus, the hypusine biosynthetic steps, deoxyhypusine synthesis and deoxyhypusine hydroxylation present special potential targets for intervention in cellular proliferation. Several inhibitors of the enzymes deoxyhypusine synthase, and deoxyhypusine hydroxylase were developed and their cellular effects have been examined. The most potent inhibitor of deoxyhypusine synthase monoguanyl-1,7-diaminoheptane, (Ki=0.01 micromoles compared to the Km of spermidine of 4micromoles) in vitro is the most effective inhibitor of hypusine formation and growth in CHO cells (IC 50 for growth inhibition 0.3micromoles). The compound is taken up actively by the polyamine transport system. Mutant CHO cells defective in polyamine transport are resistant to growth inhibition by monoguanyl-1,7- diaminoheptane indicating that it exerts antiproliferative activity intracellularly by inhibition of hypusine synthesis. The guanylated diamines represent a new class of antiproliferative agents, the action of which is targeted toward a single specific cellular process, hypusine biosynthesis.