Biological Action of Bioactive Peptides in Milk and their Application

Abstract

Milk contains a large number of bioactive peptides with various biological activities.These peptides exist naturally in milk or derive from milk protein hydrolyses.The natural bioactive peptides found in milk include EGF,TGF,NGF,IGF Ⅰ,TGF Ⅱ,insulin et al.,which concentrations are generally higher in colostrum than in milk.These milk borne bioactive peptides are likely to survive the gastrointestinal lumen of suckling animals due to a limited protease activity in the gut of neonatal animals and the existence of protease inhibitors in the milk.Oral administration of EGF,IGF Ⅰ or insulin can stimulate gastrointestinal maturation in newborn animals.It is speculated that colostrum borne bioactive peptides may play an important role in regulating postnatal gut development in suckling neonates.The second group of bioactive peptides found in milk include casomorphins,immunostimulating peptides,and ACE inhibitory peptides.They are built into the primary structures of milk proteins and can be released by enzymatic hydrolyses.These peptides may act as potential physiological modulators during the gastrointestinal digestion of milk.

乳中含有大量不同活性的生物活性肽。這些肽或自然存在于乳中或源于乳蛋白水解后的產物。在乳中已發現自然態存在的活性肽包括 EGF、TGF、NGF、IGF- 、IGF- 、胰島素等 ,其濃度在初乳中一般比較高 ,而且因新生動物胃腸道蛋白酶的活性較低 ,乳中還存在著蛋白酶抑制劑 ,因此這些乳源性生物活性肽在新生幼畜胃腸道中比較穩定。灌 (口 )服 EGF、胰島素或 IGF- 能刺激新生幼仔胃腸道的成熟 ,推測初乳源生物活性肽在調節哺乳幼仔消化道發育中起著重要作用。乳中發現的第二類生物活性肽包括酪源嗎啡、免疫刺激肽以及 ACE-抑制肽。它們組成乳蛋白的主要結構并且能被酶水解后釋放 ,這些肽可能起著潛在的生理調節劑的作用