Thymidylyltransferases (thymidine diphospho pyrophosphorylases) are nucleotidylyltransferases that play key roles in the biosynthesis of carbohydrate components within bacterial cell walls and in the biosynthesis of glycosylated natural products. They catalyze the formation of sugar nucleotides concomitant with the release of pyrophosphate. Protein engineering of thymidylyltransferases has been an approach for the production of a variety of non-physiological sugar nucleotides. In this work, we have explored chemical approaches towards modifying the activity of the thymidylyltransferase (Cps2L) cloned from S. pneumoniae, through the use of chemically synthesized ‘activated’ nucleoside triphosphates with enhanced leaving groups, or by switching the metal ion co-factor specificity. Within a series of phosphonate-containing nucleoside triphosphate analogues, thymidylyltransferase activity is enhanced based on the acidity of the leaving group and a Brønsted-type analysis indicated that leaving group departure is rate limiting. We have also determined IC50 values for a series of bisphosphonates as inhibitors of thymidylyltransferases. No correlation between the acidity of the inhibitors (pKa) and the magnitude of enzyme inhibition was found.
                                    胸苷酰转移酶(
胸苷二
磷酸焦磷酸化酶)是一种核苷酸转移酶,在细菌细胞壁内
碳水化合物成分的
生物合成以及糖基化
天然产物的
生物合成中发挥着关键作用。它们在催化糖核苷酸形成的同时释放
焦磷酸。
胸苷基转移酶的蛋白质工程是生产各种非生理糖核苷酸的一种方法。在这项工作中,我们通过使用
化学合成的具有增强离去基团的 "活化 "
三磷酸核苷,或通过改变
金属离子辅助因子的特异性,探索了改变从肺炎双球菌克隆的
胸苷基转移酶(Cps2L)活性的
化学方法。在一系列含
膦酸盐的
三磷酸核苷类似物中,胸
腺苷酸转移酶的活性根据离去基团的酸度而增强,布氏分析表明离去基团的离去是限制速率的。我们还测定了作为胸
腺苷酸转移酶
抑制剂的一系列
双膦酸盐的 IC50 值。我们没有发现
抑制剂的酸性(pKa)与酶抑制作用的大小之间有任何关联。