Department of Nutrition and Food Science, Faculty of Pharmacy, University of Granada, Campus de Cartuja s/n, 18071, Granada, Spain.
Department of Food and Nutritional Sciences, The University of Reading, Whiteknights, PO Box 226, Reading, RG6 6AP, UK.
Anal Bioanal Chem. 2018 Jun;410(15):3597-3606. doi: 10.1007/s00216-018-0983-0. Epub 2018 Mar 10.
In this study, ultrafiltered goat milks fermented with the classical starter bacteria Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarus subsp. thermophilus or with the classical starter plus the Lactobacillus plantarum C4 probiotic strain were analyzed using ultra-high performance liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) and/or high performance liquid chromatography-ion trap (HPLC-IT-MS/MS). Partial overlapping of the identified sequences with regard to fermentation culture was observed. Evaluation of the cleavage specificity suggested a lower proteolytic activity of the probiotic strain. Some of the potentially identified peptides had been previously reported as angiotensin-converting enzyme (ACE) inhibitory, antioxidant, and antibacterial and might account for the in vitro activity previously reported for these fermented milks. Simulated digestion of the products was conducted in the presence of a dialysis membrane to retrieve the bioaccessible peptide fraction. Some sequences with reported physiological activity resisted digestion but were found in the non-dialyzable fraction. However, new forms released by digestion, such as the antioxidant α-casein YFYPQL, the antihypertensive α-casein YQKFPQY, and the antibacterial α-casein LKKISQ, were found in the dialyzable fraction of both fermented milks. Moreover, in the fermented milk including the probiotic strain, the k-casein dipeptidyl peptidase IV inhibitor (DPP-IV) INNQFLPYPY as well as additional ACE inhibitory or antioxidant sequences could be identified. With the aim of anticipating further biological outcomes, quantitative structure activity relationship (QSAR) analysis was applied to the bioaccessible fragments and led to potential ACE inhibitory sequences being proposed. Graphical abstract Ultrafiltered goat milks were fermented with the classical starter bacteria (St) and with St plus the L. plantarum C4 probiotic strain. Samples were analyzed using HPLC-IT-MS/MS and UPLC-Q-TOF-MS/MS. After simulated digestion and dialysis, some of the active sequences remained and new peptides with reported beneficial activities were released.
本研究采用超高效液相色谱-四极杆飞行时间串联质谱（UPLC-Q-TOF-MS/MS）和/或高效液相色谱-离子阱串联质谱（HPLC-IT-MS/MS）分析了经经典发酵菌（乳酸乳球菌亚种保加利亚乳杆菌和唾液链球菌亚种嗜热链球菌）或经典发酵菌加植物乳杆菌 C4 益生菌株发酵的超滤山羊奶。观察到发酵培养物中鉴定序列的部分重叠。对裂解特异性的评估表明益生菌株的蛋白水解活性较低。一些潜在鉴定的肽先前被报道具有血管紧张素转换酶（ACE）抑制、抗氧化和抗菌活性，可能是这些发酵乳先前报道的体外活性的原因。在存在透析膜的情况下进行产物模拟消化，以回收可生物利用的肽段。一些具有报道的生理活性的序列抵抗消化，但存在于不可透析的部分。然而，通过消化释放的新形式，如抗氧化α-酪蛋白 YFYPQL、降压α-酪蛋白 YQKFPQY 和抗菌α-酪蛋白 LKKISQ，在两种发酵乳的可透析部分均有发现。此外，在含有益生菌株的发酵乳中，还可以鉴定到κ-酪蛋白二肽基肽酶 IV 抑制剂（DPP-IV）INNQFLPYPY 以及其他 ACE 抑制或抗氧化序列。为了预测进一步的生物学结果，应用定量构效关系（QSAR）分析对可生物利用的片段进行分析，并提出了潜在的 ACE 抑制序列。
