Generation of bioactive peptides from meat proteins during aging and intestinal digestion

本研究旨在研究肉类老化和肠道消化过程中蛋白酶对肉类蛋白产生生物活性肽的影响。由于我们的研究表明，在老化或贮藏过程中，牛肉和猪肉产品的生物活性（如ACE抑制活性）有所增加，因此证实了生物活性肽的产生是在老化或储存过程中发生的。从肉蛋白中提取的许多生物活性肽（如抗高血压肽、抗氧化肽、益生元肽、阿片肽）已在本研究中得到鉴定。例如，从猪肉蛋白中发现了几种新的抗氧化肽。在这些抗氧化肽中，活性最高的肽是Asp-Leu-Tyr-Ala。该肽在体内也显示出一些显著的活性（如抗疲劳活性）。由于四种单独氨基酸的混合物没有显示出生物活性，因此Asp-Leu-Tyr-Ala的四肽结构对其活性至关重要。通过消化道酶的作用，Asp-Leu-Tyr-Ala生成三肽（Leu-Tr-Ala）。Leu-Try-Ala与Asp-Leu-Tyr-Ala在体外和体内均表现出相似的活性。在另一项实验中，在猪肉蛋白消化液中发现了一种新的生物活性肽——Glu-Leu-Met。Glu-Leu-Met是第一个通过酶消化从食物蛋白质中产生的益生元（促进双歧杆菌生长）肽。由于这种肽对消化酶具有高度的抗性，因此它可能是一种很有前途的益生元成分。由于在胃肠道蛋白质水解过程中，食物蛋白质会释放出生物活性肽，因此目前正在进行进一步的研究，以确定肠道中肉类蛋白质产生的生物活性肽。

This research project has been conducted to investigate the generation of bioactive peptides from meat proteins by proteases during meat aging and intestinal digestion. Since our studies showed an increase in bioactivities (e.g., ACE inhibitory activity) of beef and pork products during aging or strage, the generation of bioactive peptides was onfirmed to occur by aging or storage. Many bioacitive peptides (e.g., antihypertensive peptides, antioxidative peptides, prebiotic peptides, opioide peptides) derived from meat proteins have been identified in this study. For example, several novel antioxidative peptides generated from pork proteins were discovered. Of these antioxidative peptides, the peptide, which showed the highest activity, was Asp-Leu-Tyr-Ala. This peptide also showed some remarkable activities (e.g., anti-fatigue activity) in vivo. Since the mixture of four individual amino acids did not show the biological activity, the tetra peptide-structure of Asp-Leu-Tyr-Ala is critical for its activity. By the treatment of digestive tract enzymes, Asp-Leu-Tyr-Ala generated tripeptide (Leu-Tr-Ala). Leu-Try-Ala showed similar activities with Asp-Leu-Tyr-Ala both in vitro and in vivo experiments. In another experiment, a novel bioactive peptide, Glu-Leu-Met was identified in the pork protein digest. Glu-Leu-Met is the first prebiotic (Bifidobacterium growth-promoting) peptide generated from food proteins by enzymatic digestion. Since this peptide is highly resistant to digestive enzymes, it would be a promising prebiotic component. As bioactive peptides would be liberated from food proteins during gastrointestinal proteolysis, further studies are now in progress to identify the generation of such peptides from meat proteins in the intestinal tracts.