title: Production of dipeptidyl peptidase IV inhibitory peptides from defatted rice bran.
abstract: The insulinotropic hormone glucagon-like peptide-1 is metabolised extremely rapidly by the ubiquitous enzyme dipeptidyl peptidase IV (DPP-IV). Therefore, human DPP-IV is a key regulator involved in the prevention and treatment of type 2 diabetes. To simplify the method of producing an inhibitory peptide against DPP-IV, we focused on rice bran (RB) as a source and subjected proteins from defatted RB to enzymatic proteolysis using 2 commercial enzymes. The RB peptides produced with Umamizyme G exhibited 10 times the inhibitory activity as those produced with Bioprase SP. The half-maximal inhibitory concentration (IC(50)) value of the RB peptides was 2.3 ± 0.1mg/ml. Leu-Pro and Ile-Pro were identified as the inhibitory peptides among the RB peptides produced with Umamizyme G. Ile-Pro was the strongest DPP-IV inhibitor among the 15 Xaa-Pro dipeptides and Pro-Ile tested. Ile-Pro competitively inhibited DPP-IV (K(i)=0.11 mM). Mass spectrometry indicated that the contents of Leu-Pro and Ile-Pro in the RB peptides were 2.91 ± 0.52 μg/mg.
authors.affiliation: Okayama Prefectural Technology Center for Agriculture, Forestry, and Fisheries, Research Institute for Biological Sciences (RIBS), Okayama, 7549-1 Kibichuo-cho, Kaga-gun, Okayama 716-1241, Japan. hatanaka@bio-ribs.com
authors.forename: Tadashi
authors.initials: T
authors.lastname: Hatanaka
authors.forename: Yosikazu
authors.initials: Y
authors.lastname: Inoue
authors.forename: Jiro
authors.initials: J
authors.lastname: Arima
authors.forename: Yuya
authors.initials: Y
authors.lastname: Kumagai
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Usuki
authors.forename: Kayoko
authors.initials: K
authors.lastname: Kawakami
authors.forename: Masayo
authors.initials: M
authors.lastname: Kimura
authors.forename: Takafumi
authors.initials: T
authors.lastname: Mukaihara
mesh_terms: D018819:Dipeptidyl Peptidase 4 / Q000737:chemistry / Q000378:metabolism; D054873:Dipeptidyl-Peptidase IV Inhibitors / Q000737:chemistry* / Q000302:isolation & purification; D006801:Humans; D007700:Kinetics; D012275:Oryza / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification; D012639:Seeds / Q000737:chemistry
chemical_list: D054873:Dipeptidyl-Peptidase IV Inhibitors; D010455:Peptides; D010936:Plant Extracts; D018819:Dipeptidyl Peptidase 4