微生物を由来とする機能性タンパク質の医用工学的応用に関する研究

A study on novel functional protein tool derived from bacterial products was carried out. This
tool is composed of two parts, a functional domain to exhibit regulated cytotoxicy and a targeting
domain to recognize the target cell, and these domains are connected with a chemical linker. A
Pseudomonas aeruginosa exotoxin A (ETA) deficient in its receptor-binding domain, named
ΔBD-ETA, was adopted as the functional domain. ΔBD-ETA was expressed in Escherichia coli
expression system and purified by Ni-NTA affinity chromatography. Purified ΔBD-ETA indicates no
cytotoxity to human lung carcinoma A549 at the concentrations showing severe cytotoxity of
wild-type ETA. A recombinant single chain Fv (ScFv) derived from anti-carcinoembryonic
antigen (CEA) antibody, named anti-CEA-ScFv, was selected as the targeting domain. In contrast
to ΔBD-ETA, anti-CEA-ScFv was difficult to express stably as functional targeting domain against
CEA. Thus, the construction of functional protein tool has not been completed at the moment.
However, further attempts to overcome the problem including the preparation of
alternative/improved functional protein tool are in progress.