Production of protein solid material

A method for producing a protein crystal, the method comprising:

• step (a) of adding a nucleic acid encoding a crystalline protein to a protein synthesis system;
• step (b) of incubating the protein synthesis system for a predetermined time until the crystalline protein encoded by the added nucleic acid is expressed and the expressed crystalline protein completes the formation of crystals;
• and
• step (c) of obtaining the crystals,
• wherein the protein synthesis system is a cell-free protein synthesis system,
• the predetermined time in step (b) is 64 hours or less,
• the temperature of the protein synthesis system is 10° C. or higher, and
• the crystalline protein is one selected from the group consisting of the following (i) to (viii):
• (i) a protein comprising the amino acid sequence set forth in SEQ ID NO:1, or a protein comprising an amino acid sequence in which 1 to 50 amino acids have been deleted, substituted, or added in the amino acid sequence set forth in SEQ ID NO:
• 1, the protein having a polyhedron-forming ability;
• (ii) a protein comprising the amino acid sequence set forth in SEQ ID NO:2, or a protein comprising an amino acid sequence in which 1 to 50 amino acids have been deleted, substituted, or added in the amino acid sequence set forth in SEQ ID NO:2, the protein having a polyhedron-forming ability;
• (iii) a protein comprising the amino acid sequence set forth in SEQ ID NO:18, or a protein comprising an amino acid sequence in which 1 to 50 amino acids have been deleted, substituted, or added in the amino acid sequence set forth in SEQ ID NO:
• 18, the protein having a crystal-forming ability;
• (iv) a protein comprising the amino acid sequence set forth in SEQ ID NO:19, or a protein comprising an amino acid sequence in which 1 to 50 amino acids have been deleted, substituted, or added in the amino acid sequence set forth in SEQ ID NO:
• 19, the protein having a crystal-forming ability;
• (v) a protein comprising the amino acid sequence set forth in SEQ ID NO:22, or a protein comprising an amino acid sequence in which 1 to 50 amino acids have been deleted, substituted, or added in the amino acid sequence set forth in SEQ ID NO:22, the protein having a crystal-forming ability;
• (vi) a protein comprising the amino acid sequence set forth in SEQ ID NO:24, or a protein comprising an amino acid sequence in which 1 to 20 amino acids have been deleted, substituted, or added in the amino acid sequence set forth in SEQ ID NO:24, the protein having a crystal-forming ability;
• (vii) a fusion protein comprising a protein selected from any one of (i) to (vi) and a target peptide, the fusion protein having a crystal-forming ability;
• and
• (viii) a fusion protein comprising the amino acid sequence set forth in SEQ ID NO:1, wherein the 70th amino acid to the 77th amino acid of the amino acid sequence has been substituted with a target peptide, and/or wherein 1 to 50 amino acids have been deleted, substituted, or added in the fusion protein, the fusion protein having a polyhedron-forming ability.