A low concentration of -CN f58-76 or related fragments in the additional sodium caseinate hydrolysates cannot be excluded. The highest ACE-inhibitory activity of some peptides corresponded to the concentration of the ACE inhibitor (spp., F19 was ca. 50 g/ml. Once generated, the bioactive peptides were resistant to further degradation by proteinase of PR4 or by trypsin and chymotrypsin. During the last decade, fundamental studies possess opened a new field of study dealing with bioactive or biogenic substances derived from foods. Bioactive substances of food source are considered to be dietary parts which exert a regulatory activity in the human being organism, beyond fundamental nutrition (30). Milk naturally consists Diflorasone of an array of bioactivities due to lysozyme, lactoferrin, immunoglobulins, growth factors, and hormones, which are secreted in their active form from the mammary gland (36). In addition, many bioactivities in milk are encrypted within the primary structure of milk proteins, requiring proteolysis for his or her launch from precursors. Proteolysis may launch these biogenic peptides during gastrointestinal transit or during food processing (for a review, see referrals 7, 20, and 30). These biological activities include opioid agonist and antagonist peptides, hypotensive peptides which inhibit angiotensin-I-converting enzyme (ACE), and mineral binding, immunomodulatory, antibacterial, and antithrombotic peptides Diflorasone (12, 13, 29). Generally, three strategies are used to determine and characterize biologically active peptides: (i) isolation from in vitro enzymatic digests of precursor proteins; (ii) isolation from in vivo gastrointestinal digests of precursor proteins; and (iii) chemical synthesis based on combinatorial library designs of peptides which have a structure identical to Diflorasone that of those known to be bioactive (4, 30). Antihypertensive peptides inhibit ACE (peptidyl-dipeptide hydrolase; EC ACE is definitely a multifunctional ectoenzyme that is located in different cells and plays a key physiological part in the renin-angiotensin, kallikrein-kinin, and immune systems. The enzyme is responsible for the increase in blood pressure by transforming angiotensin-I to the potent vasoconstrictor, angiotensin-II, and by degrading bradykinin, a vasodilatory peptide, and enkephalins (34). After the finding of competitive ACE inhibitors in snake venom (15), several ACE-inhibitory peptides were recognized by in vitro enzymatic digestion of milk proteins or chemical synthesis of peptide analogues (20). It is Diflorasone generally approved that the total antibacterial effect in milk is greater than the sum of the individual contributions of immunoglobulin and nonimmunoglobulin defense proteins or peptides. This may be due to the synergistic activity of naturally happening proteins and peptides, in addition to peptides generated from inactive protein precursors (7). Antimicrobial peptides are observed throughout nature. In mammals, they are found both in the epithelial surfaces and within granules of phagocytic cells. They may be an important component of innate defenses, since in addition to killing microorganisms, they are able to modulate inflammatory reactions (10). Antimicrobial milk proteins, such as lactoferrin, its pepsin-derived peptide fragments (lactoferricins), casocidin-I, and isracidin were described in the early literature (5, 23, 46). More recently, antimicrobial and antifungal peptides were designed by using combinational libraries (4), and novel antibacterial peptides were indicated in vivo in (44) or purified from a pepsin break down of human milk which corresponds to -casein (CN) f63-117 (24). Compared to the additional potential functions of bioactive peptides, this remains to be further analyzed due to the interesting features of antimicrobial peptides. Two additional aspects deserve further consideration with this field: the part of lactic acid bacteria in generating bioactive peptides during food processing and the Diflorasone susceptibilities of milk from different varieties to providing as precursors of bioactive peptides. Proteolytic activation Tmem9 of bioactive sequences by lactic acid bacteria has been debated recently due to the great advantage of using food-grade microorganisms to enrich foods with bioactive substances (20). The proteolytic system of.