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Effects of tripeptides derived from milk proteins on polymorphonuclear oxidative and phosphoinositide metabolisms

Effects of tripeptides derived from milk proteins on polymorphonuclear oxidative and phosphoinositide metabolisms. Migliore-Samour, Daniele; Roch-Arveiller, Monique; Tissot, Michele; Jazziri, M'hamed; Keddad, Karim; Giroud, Jean Paul; Jolles, Pierre (Lab. Proteines, Univ. Paris V, Paris F-75270, Fr.). Biochem. Pharmacol., 44(4), 673-80 (English) 1992. CODEN: BCPCA6. ISSN: 0006-2952. DOCUMENT TYPE: Journal CA Section: 17 (Food and Feed Chemistry) Section cross-reference(s): 13, 15 The tripeptide GLF (glycyl-leucyl-phenylalanine) was isolated from human milk proteins. This peptide increased phagocytosis by human and murine macrophages and protected mice against Klebsiella pneumonia infection. Specific binding sites on human polymorphonuclear leukocytes (PMNs) have been demonstrated recently. The aim of the present research was to study the action of this peptide on rat and human PMN oxidative burst and to investigate the consequences of cell stimulation on polyphosphoinositide hydrolysis. A biphasic stimulating concn.-dependent effect of GLF on PMN chemiluminescence and superoxide anion generation was demonstrated.There are some reagents like 20368-24-5 is used in this study. One of the peaks of the oxidative response occurred around 10-9 M, which correlates with the Kd of high affinity receptors of GLF. The other max., around 10-4 M, might be due to the hydrophobic nature of the tripeptide. O2- generation mimicked the phorbol myristate acetate response: after a lag period of 2-5 min, O2- release gradually increased for 10-15 min until a plateau was reached. Furthermore, GLF enhanced phosphoinositide breakdown with maximal IP3 prodn. at 10-7 M. Various analogs of GLF were synthesized to define the relative importance of the different amino acids and their position in the tripeptide mol.: glycyl-phenylalanine-leucine was devoid of biol. properties but enhanced the activity of GLF on the metabolic burst at high concns.; peptides leucyl-leucyl-phenylalanine and leucyl-leucyl-tyrosine, which displaced GLF from its specific membrane receptors, exerted stimulating effects on PMN oxidative and phosphoinositide metabs. It is quite conceivable that these short peptides, which may be generated in the newborn during digestion and which are able to stimulate phagocytic cells, are implicated in the defense of the neonate immature organism against infection. .