[#1993-03] Purification of a copper binding peptide from the mushroom Grifola frondosa and its effect on copper absorption, Iwao Shimaoka et al.

Purification of a copper binding peptide from the mushroom Grifola frondosa and its effect on copper absorption

Iwao Shimaoka,* Junko Kodama,* Kohsuke Nishino,t and Yoshinori Itokawa*

*Department of Hygiene, Faculty of Medicine, Kyoto University; and tDepartment of Home Economics, Dohshisha Women’s College, Kyoto, Japan

The present studies were undertaken to investigate the effect of a copper binding peptide on copper bioavailability. This peptide was extracted from the fruit bodies of the mushroom, Grifola frondosa ( maitake ), and purified to a single peptide using gel filtration and ion exchange chromatography. The purified copper binding peptide was an acidic peptide of molecular weight 2,240 in which four amino acids (aspartic acid, glutamic acid, serine, and glycine) occupied about 84% of total residues, and possessed specific properties to bind copper or to maintain copper in the soluble state at physiological pH. Molar ratio of the peptide and copper binding was 1.01. This peptide, when added to the mucosal solution in the in vitro experiment using everted intestinal sac of the rat, could significantly increase the amount of copper transported across the intestinal cells, compared with the addition of casein or its digestive peptides. These data suggest that this peptide enhances copper absorption in the small intestinal tract by increasing the amount of soluble copper.