title: Pressure/temperature combined treatments of precursors yield hormone-like peptides with pyroglutamate at the N terminus.
abstract: Peptides containing the cyclic product of glutamine at the N terminus are usually biologically active. If the cyclization of glutamine was associated with a volume reduction, pressure should displace the equilibrium in the direction of the lower volume. Here, results in model solutions and in whey are discussed, showing that the theorized cyclization of glutamine in Gln-His-ProNH(2) or Gln-Leu-ProNH(2) is significantly accelerated during the application of heat and even more strongly when elevated temperature and pressure combinations are used. The reaction rate depended on the intensity of the pressure treatment, the pH, and the nature of the amino acids adjacent to glutamine. The products of the reaction were identified as thyrotropin-releasing hormone (TRH) and [Leu(2)]TRH. The reported reactions could affect the naturally balanced concentration of short-chain peptides in foods and therefore induce unpredictable biological effects.
authors.affiliation: Institute of Chemistry and Biology, Federal Research Centre for Nutrition, Haid-und-Neustrasse 9, D-76131 Karlsruhe, Germany. veli.fernandez@bfe.uni-karlsruhe.de
authors.forename: Avelina
authors.initials: A
authors.lastname: Fernández García
authors.forename: Peter
authors.initials: P
authors.lastname: Butz
authors.forename: Bernhard
authors.initials: B
authors.lastname: Trierweiler
authors.forename: Heike
authors.initials: H
authors.lastname: Zöller
authors.forename: Joachim
authors.initials: J
authors.lastname: Stärke
authors.forename: Eberhard
authors.initials: E
authors.lastname: Pfaff
authors.forename: Bernhard
authors.initials: B
authors.lastname: Tauscher
mesh_terms: D003500:Cyclization; D005973:Glutamine / Q000737:chemistry; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D036361:Peptide Hormones / Q000737:chemistry*; D011312:Pressure; D011498:Protein Precursors / Q000737:chemistry*; D011761:Pyrrolidonecarboxylic Acid / Q000032:analysis*; D012996:Solutions; D013973:Thyrotropin-Releasing Hormone / Q000737:chemistry
chemical_list: D036361:Peptide Hormones; D011498:Protein Precursors; D012996:Solutions; D005973:Glutamine; D013973:Thyrotropin-Releasing Hormone; D011761:Pyrrolidonecarboxylic Acid