It is intended to provide a method of conveniently screening a novel protein or a novel partial sequence protein having a blocking ability based on amino acid sequence data; and a protein achieving an improved blocking efficiency that can be expressed on a large scale in Escherichia coli. A method of screening a novel protein or a novel partial sequence protein having a blocking ability based on amino acid sequence data; a protein characterized by achieving an improved blocking efficiency owing to an amino acid sequence modification; and a method of utilizing the protein.