Capsule protein and multimeric complex composition thereof, and pharmaceutical composition using same

Abstract

There has been an idea to load a pharmaceutical agent in a barrel structure of a lipocalin-type prostaglandin D synthase, and to seal the pharmaceutical agent in the barrel structure by introducing a disulfide bond between H-helix and E-F loop. However, in some cases the pharmaceutical agent is released through a gap in the vicinity of the open mouth of the barrel structure. The present capsule protein has substitution of alanine residue for a cysteine residue of the active center of the human lipocalin-type prostaglandin D synthetase. The protein further has substitution of barrier amino acid residue(s) for at least one amino acids of D strand. The barrier amino acids in the D-strand, located in the vicinity of the open mouth of its barrel structure suppresses the leak of the pharmaceutical agent.