Amino Yusuke, Wakabayashi Hidehiko, Akashi Satoko, Ishiwatari Yutaka
a Institute for Innovation , Ajinomoto Co., Inc. , Kawasaki , Japan.
b Institute of Food Sciences and Technologies , Ajinomoto Co., Inc. , Kawasaki , Japan.
Biosci Biotechnol Biochem. 2018 Mar;82(3):383-394. 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.
研究了含硫氨基酸的γ-谷氨酰肽的结构、风味修饰作用及钙敏感受体（CaSR）活性。通过将从大蒜中分离得到的γ-L-谷氨酰-S-(2-丙烯基)-L-半胱氨酸（γ-L-谷氨酰-S-烯丙基-L-半胱氨酸）及其亚砜的核磁共振谱与用化学方法制备的 authentic 肽的谱图进行比较，确定了它们的化学结构，包括N端谷氨酸的连接方式。质谱分析还能够通过其特征性裂解确定谷氨酰二肽中的连接方式。在感官评价中，这些肽在鲜味溶液中表现出风味修饰作用（持续性），但不如谷胱甘肽明显且与之相似。此外，这些肽由于含硫结构而具有固有风味，这可能部分解释了它们的风味修饰作用。在CaSR检测中，γ-L-谷氨酰-S-甲基-L-半胱氨酰甘氨酸活性最高，这表明γ-谷氨酰肽中第二个氨基酸残基处存在中等大小的脂肪族取代基可增强CaSR活性。
