3 .Construction of the cloning vector pSP-hANGAngiostatin PCR product , digested by Xhol + EcoRI,were ligated with vector pSP71 digested by the same restriction enzyme to construct a recombinant plasmid pSP-hANG.

• 克隆载体pSP-hANG的构建：纯化的hANG PCR产物和载体pSP71分别经XhoI和EcoRI双酶切、连接，构建载体pSP-hANG。