Structural analysis and taste evaluation of γ-glutamyl peptides comprising sulfur-containing amino acids

• Published in: Bioscience, biotechnology, and biochemistry Vol. 82; no. 3; pp. 383 - 394
• Main Authors: Amino, Yusuke, Wakabayashi, Hidehiko, Akashi, Satoko, Ishiwatari, Yutaka
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 01.03.2018; Oxford University Press
• Subjects: Boc: tert-butoxycarbonyl; Bu: tert-butyl; calcium-sensing receptor; CaSR: calcium-sensing receptor; Cbz: benzyloxycarbonyl; CDI: collision induced dissociation; DCC: N,N'-dicyclohexylcarbodiimide; DCHA: dicyclohexylamine; ESI-MS/MS: electrospray ionization tandem mass spectrometry; FAB-MS/MS: fast atom bombardment tandem mass spectrometry; FABMS: fast atom bombardment mass spectrometry; FDMS: field desorption mass spectrometry; flavor-modifying effect; GPCRs: G protein-coupled receptors; GSH:γ-L-glutamyl-L-cysteinylglycine (glutathione); IMP: 5'-inosinate; MSG: monosodium glutamate; NHS: N-hydroxysuccinimide; SIMS: secondary-ion mass spectrometry; spectroscopic analysis; sulfur-containing amino acid; Tfa: trifluoroacetyl; TMS: tetramethylsilane; TSP: sodium 3-trimethylsilylpropionate-2,2,3,3-d; VFD: Venus flytrap domain; γ-Glutamyl peptide; CaSR: calcium-sensing receptor; ESI-MS/MS: electrospray ionization tandem mass spectrometry; calcium-sensing receptor; γ-Glutamyl peptide; CDI: collision induced dissociation; dicyclohexylcarbodiimide; butyl; SIMS: secondary-ion mass spectrometry; IMP: 5’-inosinate; TMS: tetramethylsilane; Boc; VFD: Venus flytrap domain; GSH:γ-L-glutamyl-L-cysteinylglycine (glutathione); FAB-MS/MS: fast atom bombardment tandem mass spectrometry; flavor-modifying effect; FDMS: field desorption mass spectrometry; GPCRs: G protein-coupled receptors; DCC; NHS: N-hydroxysuccinimide; butoxycarbonyl; sulfur-containing amino acid; FABMS: fast atom bombardment mass spectrometry; spectroscopic analysis; Bu; TSP: sodium 3-trimethylsilylpropionate-2,2,3,3-d; Tfa: trifluoroacetyl; MSG: monosodium glutamate; DCHA: dicyclohexylamine; Cbz: benzyloxycarbonyl; TSP: sodium 3-trimethylsilylpropionate-2,2,3,3-d4; tBu: tert-butyl; DCC: N,N’-dicyclohexylcarbodiimide; tBoc: tert-butoxycarbonyl
• ISSN: 0916-8451; 1347-6947
• DOI: 10.1080/09168451.2018.1436433

The structures, flavor-modifying effects, and CaSR activities of γ-glutamyl peptides comprising sulfur-containing amino acids were investigated. The chemical structures, including the linkage mode of the N-terminal glutamic acid, of γ-L-glutamyl-S-(2-propenyl)-L-cysteine (γ-L-glutamyl-S-allyl-L-cysteine) and its sulfoxide isolated from garlic were established by comparing their NMR spectra with those of authentic peptides prepared using chemical methods. Mass spectrometric analysis also enabled determination of the linkage modes in the glutamyl dipeptides by their characteristic fragmentation. In sensory evaluation, these peptides exhibited flavor-modifying effects (continuity) in umami solutions less pronounced but similar to that of glutathione. Furthermore, the peptides exhibited intrinsic flavor due to the sulfur-containing structure, which may be partially responsible for their flavor-modifying effects. In CaSR assays, γ-L-glutamyl-S-methyl-L-cysteinylglycine was most active, which indicates that the presence of a medium-sized aliphatic substituent at the second amino acid residue in γ-glutamyl peptides enhances CaSR activity. Structural analyses and taste evaluations of g-L-glutamyl-S-(2-propenyl)-L-cysteine and its sulfoxide isolated from garlic and related peptides were performed using authentic chemically synthesized samples.