Synthesis of papain in Escherichia coli.

We have transferred the cloned papain genetic information into an expression vector (pT7-7) regulated by the T7-promoter and have obtained in vitro expression as well as expression in Escherichia coli. In Western blots the proteins produced are immunologically recognizable as papain. Multiple forms of specific but differing sizes are detected, suggesting either that initiation can occur at more than one of the upstream methionines, or that the enzyme is processed after synthesis.