Method to produce high levels of methioninase

摘要

The present invention discloses the cloning of a methioninase- encoding nucleic acid molecule from Pseudomonas putida and the construction of high-level expression modules containing the methioninase- encoding nucleic acid molecule. The invention further provides expression modules that use the T7 RNA polymerase promoter to express the isolated methioninase-encoding nucleic acid molecules. Expression modules employing the T7 promoter were found to produce unexpectedly high levels of methioninase. The present invention further provides purification methods to obtain highly pure, endotoxin free methioninase, chemically modified forms of methioninase, crystallized methioninase and lyophilized methioninase preparations. The present invention further provides therapeutical methods using the disclosed recombinant methioninase preparations.