title: Identification of pyroglutamyl peptides in Japanese rice wine (sake): presence of hepatoprotective pyroGlu-Leu.
abstract: Japanese rice wine, sake, is made from steamed rice, water, and lactic acid by "multiple parallel fermentation" with mold (Aspergillus oryzae) and yeast (Saccharomyces cerevisiae). Nineteen pyroglutamyl peptides were identified in commercially available sake. Among them, pyroGlu-Leu and pyroGlu-Gln were the major constituents. PyroGlu-Leu has been demonstrated to attenuate hepatitis and colitis in animal models. Commercial products (n = 5) contained pyroGlu-Leu at concentrations ranging from 40 to 60 μM (10-15 mg/L). The pyroGlu-Leu content in sake mash increased during the fermentation processes. However, no pyroGlu-Leu was produced by yeast inoculated into preheated mash. Furthermore, addition of (13)C-Leu to the mash did not increase the ratio of pyroGlu-(13)C-Leu to pyroGlu-(12)C-Leu. On the other hand, digestion of steamed rice with A. oryzae proteases increased the pyroGlu-Leu content. These results indicate that pyroGlu-Leu in sake is produced from rice proteins by digestion with A. oryzae proteases.
authors.affiliation: Graduate School of Life and Environmental Sciences, Kyoto Prefectural University , 1-5 Shimogamo, Kyoto 606 8522, Japan.
authors.forename: Tamami
authors.initials: T
authors.lastname: Kiyono
authors.forename: Kiyoo
authors.initials: K
authors.lastname: Hirooka
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Sunao
authors.initials: S
authors.lastname: Kuniishi
authors.forename: Maho
authors.initials: M
authors.lastname: Ohtsuka
authors.forename: Shikou
authors.initials: S
authors.lastname: Kimura
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Park
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Kenji
authors.initials: K
authors.lastname: Sato
mesh_terms: D001236:Aspergillus oryzae / Q000378:metabolism; D004151:Dipeptides / Q000032:analysis*; D005285:Fermentation; D012275:Oryza; D010447:Peptide Hydrolases / Q000378:metabolism; D010455:Peptides / Q000032:analysis* / Q000737:chemistry; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D014920:Wine / Q000032:analysis* / Q000382:microbiology
chemical_list: D004151:Dipeptides; D010455:Peptides; C041765:pyroglutamylleucine; D010447:Peptide Hydrolases; D011761:Pyrrolidonecarboxylic Acid