生物素化ATP硫酸化酶的表达、固定化与应用

现代大规模焦测序技术的产生是DNA测序技术的一次革命，其关键技术之一是得到高活性的、固定于磁性微球表面的ATP硫酸化酶．生物素化的ATP硫酸化酶可以通过生物素与亲和素之间的特异结合特性固定在包被亲和素的磁性微球表面，但是利用化学修饰法将ATP硫酸化酶进行生物素化修饰很可能会影响酶的活性．利用融合表达策略，将大肠杆菌生物素酰基载体蛋白C端87个氨基酸肽段(BCCP87)与ATP硫酸化酶在大肠杆菌内融合表达，经SDS-PAGE和Western blot分析，表达的融合蛋白分子质量约为64 ku，并且能够在大肠杆菌内被生物素化．生物素化的ATP硫酸化酶能够与亲和素包被的磁珠结合，固定后的ATP硫酸化酶具有活性，并且能够用于定量检测焦磷酸盐(PPi)和焦测序，为今后建立高通量大规模焦测序系统提供了一个有效的工具酶．

Expression, immobilization and application of biotinylated ATP sulfurylase

The modern large-scale pyrosequencing technology is a revolution of DNA sequencing. One of the key points in this technology is to get an ATP sulfurylase immobilized on the surface of magnetic beads and with a high activity. Biotinylated ATP sulfurylase can be immobilized on magnetic beads coated with streptavidin through the specific conjunction between biotin and streptavidin, but using chemical modification method to biotinylate ATPS will affect the activity of the enzyme. ATP sulfurylase fused with the carboxyl terminal 87 residues of Escherichia coli biotin carboxyl carrier protein (BCCP87) was expressed in E. coli using fusion expression strategy. Results from Western blot analysis and SDS-PAGE analysis showed that the fusion protein could be biotinylated in vivo, and the molecular mass of the fusion protein was about 64 ku. The biotinylated ATP sulfurylase could be immobilized on the surface of magnetic beads coated with strepavidin, and the immobilized ATPS could be used for quantification of PPi and pyrosequencing. An effective enzyme for the large-scale chip-based pyrosequencing system was supplied.