Kitts David D, Weiler Katie
Food Science, Food, Nutrition and Health, Faculty of Agricultural Sciences University of B.C., Vancouver, B.C. Canada, V6T-1Z4.
Curr Pharm Des. 2003;9(16):1309-23. doi: 10.2174/1381612033454883.
There are many examples of biologically active food proteins, with physiological significance beyond the pure nutritional requirements that concern available nitrogen for normal growth and maintenance. Moreover, there are many physiologically active peptides, derived by protease activity from various food protein sources; however, relationships between structural properties and functional activities have not been completely elucidated. Many bioactive peptides have in common structural properties that include a relatively short peptide residue length (e.g. 2-9 amino acids), possessing hydrophobic amino acid residues in addition to proline, lysine or arginine groups. Bioactive peptides are also resistant to the action of digestion peptidases. Antihypertensive peptides, known as Angiotensin I converting enzyme (ACE) inhibitors have been derived from milk, corn and fish protein sources. Peptides with opioid activities are derived from wheat gluten or casein, following digestion with pepsin. Exorphins, or opioid peptides derived from food proteins such as wheat and milk (e.g. exogenous sources) have similar structure to endogenous opioid peptides, with a tyrosine residue located at the amino terminal or bioactive site. Immunomodulatory peptides derived from tryptic hydrolysates of rice and soybean proteins act to stimulate superoxide anions (reactive oxygen species-ROS), which triggers non-specific immune defense systems. Antioxidant properties that prevent peroxidation of essential fatty acids have also been shown for peptides derived from milk proteins. The addition of a Leu or Pro residue to the N-terminus of a His-His, dipeptide will enhance antioxidant activity and facilitate further synergy with non-peptide antioxidants (e.g. BHT). We also show herein, that the tryptic digests of casein yielding caseinophosphopeptides exhibits both hydrophilic and lipophilic antioxidant activity due to both metal ion sequestering and quenching of ROS. The separation and purification of bioactive peptides which will involve development of automated and continuous systems is an important field for Food chemists. Much effort has been given to develop selective column chromatography methods that can replace batch methods of salting out, or using solvent extraction to isolate and purify bioactive peptides. Advances here will enable recovery of bioactive peptides with minimal destruction thus enabling utilization by returning these active peptides to functional food or specific nutraceutical applications.
具有生物活性的食物蛋白质有很多例子，其生理意义超出了与正常生长和维持所需可用氮相关的纯营养需求。此外，有许多生理活性肽是通过蛋白酶活性从各种食物蛋白质来源衍生而来的；然而，结构特性与功能活性之间的关系尚未完全阐明。许多生物活性肽具有共同的结构特性，包括相对较短的肽残基长度（例如2 - 9个氨基酸），除了脯氨酸、赖氨酸或精氨酸基团外还含有疏水氨基酸残基。生物活性肽也能抵抗消化肽酶的作用。被称为血管紧张素I转换酶（ACE）抑制剂的降压肽已从牛奶、玉米和鱼类蛋白质来源中获得。具有阿片样活性的肽是在胃蛋白酶消化后从小麦面筋或酪蛋白中获得的。外啡肽，即源自小麦和牛奶等食物蛋白质（例如外源来源）的阿片样肽，其结构与内源性阿片样肽相似，在氨基末端或生物活性位点有一个酪氨酸残基。源自大米和大豆蛋白胰蛋白酶水解物的免疫调节肽起到刺激超氧阴离子（活性氧 - ROS）的作用，从而触发非特异性免疫防御系统。源自牛奶蛋白的肽也显示出防止必需脂肪酸过氧化的抗氧化特性。在His - His二肽的N末端添加一个Leu或Pro残基将增强抗氧化活性，并促进与非肽抗氧化剂（例如丁基羟基甲苯）的进一步协同作用。我们在此还表明，酪蛋白的胰蛋白酶消化产物产生的酪蛋白磷酸肽由于金属离子螯合和ROS淬灭而表现出亲水性和亲脂性抗氧化活性。生物活性肽的分离和纯化，这将涉及自动化和连续系统的开发，是食品化学家的一个重要领域。人们已经付出了很多努力来开发选择性柱色谱方法，以取代批量盐析方法或使用溶剂萃取来分离和纯化生物活性肽。这方面的进展将能够以最小的破坏回收生物活性肽，从而通过将这些活性肽应用于功能性食品或特定的营养保健品来实现其利用。
