Ho Y K
Nucleic Acids Res. 1984 Oct 11;12(19):7599-614. doi: 10.1093/nar/12.19.7599.
In an effort to search for good methods for the enzymatic synthesis of polynucleotide analogs with antitemplate activity, 5-methylthiouridine-5'-diphosphate (ms5UDP) has been synthesized and investigated as a substrate for polynucleotide phosphorylase. While ms5UDP was polymerized at a very low rate to give a 6% yield of polynucleotides by the polynucleotide phosphorylase of Micrococcus luteus, it was utilized more efficiently by the corresponding enzyme of Escherichia coli resulting in a 15% yield of poly (5-methylthiouridylic) acid. Results of the co-polymerization of ms5UDP and UDP revealed that the ratio of 5-methylthiouridylate to uridylate residues in the polynucleotide product was lower than the ratio of ms5UDP to UDP in the substrate mixture. The 5-methylthio group conferred only minute changes on the conformation of the modified polyuridylic acid, and the complexes formed between poly-(5-methylthiouridylic) acid and poly(adenylic) acid possessed slightly higher Tm values than did the unmodified counterparts. Poly(5-methylthiouridylic) acid was a potent inhibitor of calf thymus DNA polymerase alpha.
为了寻找具有抗模板活性的多核苷酸类似物的酶促合成方法，已合成了5-甲基硫代尿苷-5'-二磷酸（ms5UDP）并将其作为多核苷酸磷酸化酶的底物进行研究。虽然ms5UDP在黄色微球菌的多核苷酸磷酸化酶作用下以非常低的速率聚合，得到6%产率的多核苷酸，但它被大肠杆菌的相应酶更有效地利用，得到15%产率的聚（5-甲基硫代尿苷酸）。ms5UDP和UDP的共聚结果表明，多核苷酸产物中5-甲基硫代尿苷酸与尿苷酸残基的比例低于底物混合物中ms5UDP与UDP的比例。5-甲基硫代基团仅使修饰的聚尿苷酸的构象发生微小变化，聚（5-甲基硫代尿苷酸）与聚（腺苷酸）形成的复合物的熔解温度（Tm）值略高于未修饰的对应物。聚（5-甲基硫代尿苷酸）是小牛胸腺DNA聚合酶α的有效抑制剂。
