Milk peptides with physiological activities. II. Opioid and immunostimulating peptides derived from milk proteins

Abstract

Summary -The presence of peptides with opioid (exorphins) or immunomodulatingactivity has been demonstrated in the sequence of milk proteins. These activities were detected using in vitro technics. Active sequences are particularly present in the sequence of caseins. Their physiological significance remains unclear. The in vivo expression of these activities is first dependent on the existence of mechanisms that modulate the degradation and absorption of the active compounds, and that permit their transport to specifie receptors. Opio id receptors are present at different levels in the gut or in the central nervous system. The action of exorphins is similar to that of other endogenous and exogenous opiates. Other peptides have been shown to act on macrophage and lymphocyte functions. The protective effect of these natural compounds constitutes an interesting potential application. témique. Des récepteurs réagissant avec les exorphines ont été trouvés aussi bien au niveau digestif, qu'au niveau du système nerveux central. Les effets observés sont analogues à ceux des autres opiacés endogènes ou exogènes. D'autres peptides agissent sur la fonction des macrophages, sur les lymphocytes B, sur les lymphocytes T. Le rôle "protecteur» de ces molécules d'origine naturelle est une voie d'étude prometteuse.protéine alimentaire 1peptide 1 opiacé 1 immunomodulation * Correspondence and reprints 242 in the intact animal after intracerebroventricular injection (Zioudriou et al, 1979; Brantl et al, 1981 Brantl et al, , 1982 Liebman et al, 1986).Several types of opiate agonistic peptides have been characterized and exert naloxone inhibitable opioid activities. The first opioid peptides described were in the 60-70 fragment of bovine~-casein (Brantl et al, 1979). This fragment and the Cterminally shortened derived peptides are called~-casomorphins, and characterized by the N-terminal sequence Tyr-Pro-PhePro. Similar peptides, called hurnan-Bcasomorphins, have been found in the 41-44, 51-58, and 59-63 fragments of humañ -casein (Brantl, 1985; Koch et al, 1985). An oe-casein exorphin was identified as the 90-96 fragment of bovine oe-casein (Loukas et al, 1983). Moreover, B-casomorphin analogs have been prepared by C-terminal amidation and amine acid substitution, in order to increase opioid potency and to modify opiate receptor specificity (Brant! et al, 1981(Brant! et al, , 1982 Liebman et al, 1986).

Effect of a Hypocaloric Diet, Increased Protein Intake and Resistance Training on Lean Mass Gains and Fat Mass Loss in Overweight Police Officers

“…Specific proteins of high biologic value and protein components, including a variety of bioactive peptides and amino acids, increase the amount of nitrogen retention for the same nitrogen intake [26]. Ingestion of the protein casein has been shown to significantly increase net protein synthesis over other proteins such as whey protein and lactoglobulin [28][29][30][31]. The mechanism appears to be due to the hormone modulating-like effects of casein peptides, which not only increase endogenous protein synthesis but also decrease endogenous protein breakdown, a characteristic not seen with other proteins studied.…”

“…Hydrolysates of the milk protein casein have recently been shown to significantly increase nitrogen retention and decrease net protein breakdown and amino acid oxidation compared to that of other protein supplements, including the milk protein whey, which is the most commonly used protein in commercially available supplements [28][29][30][31]. This process appears to be due not only to the amino acid composition of the casein protein but also to the anabolic or anticatabolic hormone-like action of some of the generated bioactive peptides [26][27][28][29][30][31].…”

Cheese as Functional Food: The Example of Parmigiano Reggiano and Grana Padano

“…There is a substantial body of evidence according to which several of the biologically active peptides released by enzymatic hydrolysis of milk proteins are very potent immunoregulatory peptides (25), aff ecting cells of the immune system, and consequently the downstream immunological responses and cellular functions (25,26).…”

Food‐derived peptides and intestinal functions

“…Di-and tripeptides are actively transported via a specific transporter (PepT1) [5], but they are also readily hydrolyzed to amino acids in the epithelial cells. Many Category 2 functions of proteins/peptides have been reported; these include lowering the blood pressure by angiotensin-converting enzyme (ACE)-inhibitory peptides [7], modulating the immune systems by immune-modulatory peptides [8], and modulating nerve functions by opioid peptides [8]. The paracellular pathway is known to be a non-degradative transport route, keeping intact the transported proteins/peptides.…”