尿苷-胞苷激酶（Uridine/cytidine kinase, UCK）作为生物体核苷酸代谢补偿途径中的重要催化剂，可以催化尿苷和胞苷磷酸化成为尿苷酸（5`-uridine monophosphate, 5`-UMP）和胞苷酸（5`-cytidine monophosphate, 5`-CMP）。利用大肠杆菌Escherichia coli BL21（DE3）分别成功克隆表达了来源于嗜热栖热菌（Thermus thermophilus HB8）以及枯草芽孢杆菌（Bacillus subtilis 168）的尿苷-胞苷激酶。对比分析了不同重组尿苷-胞苷激酶的催化特性发现，来源于嗜热栖热菌的尿苷-胞苷激酶能以鸟苷三磷酸（Guanosine 5`-triphosphate, GTP）或者腺苷三磷酸（Adenosine 5`-triphosphate, ATP）作为磷酸供体催化尿苷生成尿苷酸，而来源于枯草芽孢杆菌的尿苷-胞苷激酶只有以GTP作为磷酸供体时的催化效果较好。在优化的反应条件下，使用来源于嗜热栖热菌的尿苷-胞苷激酶，6 h可催化10 mM的尿苷和10 mM的ATP生成8.74 mM尿苷酸。研究结果表明，以ATP作为磷酸供体的尿苷-胞苷激酶可作为一种新型的催化剂用于尿苷酸的研制与生产。

Uridine/cytidine kinase (UCK), an important catalyst in the nucleotides replenishment pathway, which is responsible for the conversion of uridine and cytidine to 5'-uridine monophosphate (UMP) and 5'-cytidine monophosphate (CMP). UCK from Thermus thermophilus HB8 and Bacillus subtilis 168 was successfully cloned and expressed in Escherichia coli BL21 (DE3) respectively. The catalytic properties of different recombinant UCK were compared. Guanosine 5`-triphosphate (GTP) and adenosine 5`-triphosphate (ATP) was the main phosphate donor of UCK from Thermus thermophilus HB8, while GTP was the main phosphate donor of UCK from Bacillus subtilis 168. Under the optimized reaction conditions, 8.74 mM UMP was obtained from 10 mM uridine and 10 mM ATP in 6 h by the UCK from Thermus thermophilus HB8. The results showed that, the ATP-dependent UCK can be used in the research and production of UMP as a new catalyst.