School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia.
Ingredia SA, 51 Avenue F. Lobbedez CS 60946, 62033 Arras, France.
Food Funct. 2023 Jun 6;14(11):5442-5452. doi: 10.1039/d3fo00748k.
Mammalian milk proteins are known to encrypt antimicrobial peptides (AMPs) which can be passively released and exert bioactivity in the gastrointestinal and cardiovascular systems pre- or post-absorption, respectively. However, the contribution of 'passive' food-derived AMPs to the pool of endogenous and microbial AMPs has not been differentiated in previous research. Insight into the consequences of protein digestion and peptide bioactivity can be gained using tools. The aim of this investigation was to use methods to characterise the yields of AMPs released from major proteins in human and cow milk under infant digestion conditions, as relevant to early nutrition. The profiles of major proteins in human and cow milk from UniProtKB/Swiss-Prot, were subjected to digestion by ExPASy-PeptideCutter, and the AMP activity of resulting peptides (≥4 amino acids, AAs) evaluated with the CAMP-RF predictive tool. The mass yields and counts of absorbing (≤10 AAs) and non-absorbing (>10 AAs) AMPs, as found in human, cow and 'humanised' ratios of cow milk proteins, were quantified. The results indicated that major whey proteins from both human and cow milks displayed a higher degree of hydrolysis than caseins, consistent with their known 'fast' digestion properties. Larger albumin and lactoferrin proteins generated relatively more and/or longer peptides. Yields of AMPs from cow milk were higher than from human milk, even after standardising the ratio of whey to casein and total protein concentration, as practiced in formulations manufactured for human newborn babies. Whereas alpha-lactalbumin (2.65 g L) and lactoferrin (1.75 g L) provided the major yields of AMPs in human milk whey proteins; beta-lactoglobulin, which is unique to cow milk, released the highest yield of AMPs in cow milk (3.25 g L or 19.9% w/w of total whey protein), which may represent an important and overlooked biological function of this protein in cow milk.
哺乳动物乳蛋白中已知含有抗菌肽（AMPs），这些 AMP 可以在胃肠道和心血管系统中分别通过被动释放和发挥生物活性。然而，在以前的研究中，尚未区分“被动”食物来源的 AMPs 与内源性和微生物 AMPs 的贡献。使用工具可以深入了解蛋白质消化和肽生物活性的后果。本研究的目的是使用这些方法来描述人乳和牛乳中主要蛋白质在婴儿消化条件下释放的 AMP 的产率，这与人的早期营养有关。从 UniProtKB/Swiss-Prot 中选择人乳和牛乳的主要蛋白质进行分析，通过 ExPASy-PeptideCutter 进行消化，并使用 CAMP-RF 预测工具评估所得肽（≥4 个氨基酸，AA）的 AMP 活性。定量人乳、牛乳和“人源化”牛乳蛋白比例中吸收（≤10 AA）和非吸收（>10 AA）AMP 的质量产率和数量。结果表明，人乳和牛乳中的主要乳清蛋白比酪蛋白更易水解，这与其已知的“快速”消化特性一致。较大的白蛋白和乳铁蛋白产生相对更多和/或更长的肽。即使在标准化乳清蛋白与酪蛋白的比例和总蛋白浓度后，牛乳中 AMP 的产率仍高于人乳，这是在为人类新生儿制造的配方中所采用的做法。虽然人乳乳清蛋白中的α-乳白蛋白（2.65 g/L）和乳铁蛋白（1.75 g/L）提供了 AMP 的主要产率；但仅存在于牛乳中的β-乳球蛋白在牛乳中释放了最高产率的 AMP（3.25 g/L 或占总乳清蛋白的 19.9%w/w），这可能代表了这种蛋白质在牛乳中的一个重要而被忽视的生物学功能。
