PEG-OLIGODEOXYRIBONUCLEOTIDE CONJUGATES

带有疏水分子的拖尾寡核苷酸类似物可能 促进寡核苷酸结合物进入活细胞 从而提高反义分子抑制的效力 基因表达。然而，与之共轭的聚乙二醇的大小 寡核苷酸可能会对基因的杂交特性产生不利影响 共轭关系。已经开发了一种体外试验来评估 聚乙二醇寡核苷酸结合物与A的杂交能力 互补的HIV-TAR RNA低聚物(250个核苷酸)。 用固体载体合成寡聚脱氧核苷酸 用聚乙二醇衍生物(分子量：300、2,000或5,000)出人意料地被 轻而易举。相反，活化的聚乙二醇衍生物与 固定在固体载体上的寡核苷酸的5‘端已经被 很难。然而，在这方面取得了重大进展。 通过使用固相结合的衍生寡核苷酸来实现 带有新的亲核连接物。 虽然，聚乙二醇寡核苷酸的杂交与 具有相同碱基数目的互补DNA序列不是 受聚乙二醇尾的大小影响，聚乙二醇寡核苷酸偶联物 不能与250个碱基长的RNA低聚物杂交。消化 由聚乙二醇寡核苷酸结合物和放射性标记的艾滋病毒- 核糖核酸酶A和核糖核酸酶T1的TAR RNA显示 与聚乙二醇(分子量5,000)结合的寡核苷酸不显著 与未修饰的DNA低聚物相关的RNA杂交。而当 与聚乙二醇(MW.300)偶联的寡核苷酸杂交以及 亲本寡核苷酸与靶RNA、寡核苷酸偶联 至聚乙二醇(分子量2000)与HIV-TAR RNA杂交约50% 在同样的条件下。然而，上述化验结果并未提供 证据表明偶联物的聚乙二醇组分可能具有 包裹或缠绕RNA，作为进一步抑制的手段 翻译。尽管如此，聚乙二醇应该保护 抗核酸外切酶结合物的寡核苷酸部分。这个 α，β-寡核苷酸与聚乙二醇偶联物的效力(M.W. 300)在慢性感染患者中抑制艾滋病毒复制 人类T细胞系正在进行评估。

Tailing oligonucleotide analogues with hydrophobic molecules may facilitate the entry of the oligonucleotide conjugates into living cells and, thereby, improve the potency of antisense molecules in inhibiting gene expression. However, the size of the PEG conjugated to oligonucleotides may adversely affect the hybridization properties of the conjugates. An in vitro assay has been developed to evaluate the hybridization abilities of PEG-oligonucleotide conjugates with a complementary HIV-TAR RNA oligomer (250 nt.). The synthesis of oligodeoxyribonucleotides using a solid support derivatized with PEG (M.W.: 300, 2,000 or 5,000) has unexpectedly been facile. Conversely, the condensation of activated PEG-derivatives with the 5'-end of an oligonucleotide anchored to a solid support has been difficult. In this regard, significant progress has, however, been achieved through the use of solid-phase bound oligonucleotides derivatized with novel nucleophilic linkers. Although, the hybridization of PEG-oligonucleotide conjugates with complementary DNA sequences having equal number of nucleobases was not affected by the size of the PEG tail, PEG-oligonucleotide conjugates did not hybridize as well with the 250 bases long RNA oligomer. Digestion of hybrids composed of PEG-oligonucleotide conjugates and radiolabelled HIV- TAR RNA with ribonuclease A and ribonuclease T1 showed that the oligonucleotide conjugated with the PEG (M.W. 5,000) did not significantly hybridize with the RNA relative to an unmodified DNA oligomer. While the oligonucleotide conjugated with PEG (M.W. 300) hybridized as well as the parent oligonucleotide with the target RNA, the oligonucleotide conjugated to PEG (M.W. 2,000) hybridized to the extent of ca. 50% with HIV-TAR RNA under the same conditions. The above assay did not, however, provide evidence indicating that the PEG portion of the conjugate could have wrapped around or entangled with the RNA as a means to further suppress translation. It is, nevertheless likely that PEG should protect the oligonucleotide moiety of the conjugates against exonucleases. The potency of an alpha,beta-oligodeoxyribonucleotide conjugated to PEG (M.W. 300) toward the inhibition of HIV replication in a chronically infected human T-cell line is being evaluated.