Figure 4.

Substrate preference and specificity of thrombin and enterokinase by the coupled assay. A. coupled assay of fusion protein containing tbS or tbS’ cleaved by thrombin in the absence or presence of PMSF. B. SDS-PAGE analysis of time course cleavage of the purified fusion protein for eDAL at undesired cryptic sites by enterokinase. The fusion protein is indicated by the arrow. C. The purified fusion protein for sDAL was cleaved into two parts by enterokinase. The fusion protein and cleaved products are indicated by the arrows. D. coupled assay of time course cleavage of the purified fusion protein for sDAL by enterokinase. The activity of DAL partner was used as the control and subtracted.