Patent ID: 7033613

Claim:
A recombinant ferritin or apoferritin produced by a gene recombination technique, comprising a holding portion that is present in an internal portion of the recombinant ferritin or apoferritin and can hold a precious metal particle, and a tunnel-like channel for connecting the holding portion and an outside of the recombinant ferritin or apoferritin, wherein the recombinant ferritin or apoferritin comprises a first neutral amino acid that has a smaller molecular size than that of glutamic acid (Glu) and that of aspartic acid (Asp) in positions on an inner surface of said channel wherein said neutral amino acid substitutes for Asp and/or Glu residues which are present when unsubstituted at to residues 120 and 123 of SEQ ID NO:2; and further comprises a basic amino acid or another neutral amino acid substituted for a glutamic acid in a position on an inner surface of the holding portion in which said glutamic acid is present when unsubstituted at at least one of residues 50 , 53 , and 56 of SEQ ID NO:2.