Soy‐ghretropin, a novel ghrelin‐releasing peptide derived from soy protein

• Published in: FEBS letters 2016-08, Vol.590 (16), p.2681-2689
• Main Authors: Nakato, Junya, Aoki, Hayato, Iwakura, Hiroshi, Suzuki, Hideyuki, Kanamoto, Ryuhei, Ohinata, Kousaku
• Format: Article
• Language: English
• Subjects: Antigens, Plant - chemistry; Antigens, Plant - metabolism; Chromatography, High Pressure Liquid; Eating; food protein; ghrelin; Ghrelin - genetics; Ghrelin - isolation & purification; Ghrelin - metabolism; Globulins - chemistry; Globulins - metabolism; peptide; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Receptors, Ghrelin - genetics; Receptors, Ghrelin - metabolism; Seed Storage Proteins - chemistry; Seed Storage Proteins - metabolism; Soybean Proteins - chemistry; Soybean Proteins - isolation & purification; Soybean Proteins - metabolism; structure‐activity relationship
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1002/1873-3468.12306

We investigated exogenous secretagogues of ghrelin, which is an orexigenic hormone isolated from the stomach. We found that the tryptic digest of soy β‐conglycinin stimulated ghrelin secretion by the ghrelin‐producing cell line, MGN3‐1. We then identified a 22‐amino acid peptide corresponding to the β‐conglycinin α‐subunit(192–213) [βCGα(192–213)] from an active fraction separated by HPLC. The N‐terminal undecapeptide of βCGα(192–213), NKNPFLFGSNR, exhibited ghrelin‐releasing activity at a lower dose than that of βCGα(192–213). We named NKNPFLFGSNR ‘soy‐ghretropin’, which corresponds to βCGα(192–202). Neither [des‐N1K2]‐soy‐ghretropin nor [des‐R11]‐soy‐ghretropin stimulated ghrelin secretion; hence, both the N‐ and C‐terminal structures of soy‐ghretropin were indispensable. Orally administered soy‐ghretropin increased plasma ghrelin levels and food intake in vivo. Soy‐ghretropin is the first exogenous ghrelin‐releasing peptide derived from food protein.