Characteristics of dipeptide transport in normal and papain-treated brush border membrane vesicles from mouse intestine. II. Uptake of glycyl-L-leucine.
The characteristics of glycyl-L-leucine uptake have been studied using normal and papain-treated brush border membrane vesicles prepared from mouse small intestine. Our results show that: (1) glycyl-L-leucine is taken up into an osmotically reactive intravesicular space; (2) intact peptide transport can be studied up to 5 min without interference of hydrolytic events when using papain-treated vesicles; (3) the time course curves of glycyl-L-leucine uptake by normal and papain-treated vesicles are identical whatever the composition of the media (mannitol, NaSCN or KSCN) and do not show any overshoot phenomenon in the presence of an electrochemical gradient of Na+ (extravesicular greater than intravesicular); (4) a linear relationship exists between initial rates of dipeptide uptake and peptide concentrations; (5) peptide uptake is weakly inhibited by other di- and tri-peptides at a 60 mM concentration. We can conclude that intact peptide transport occurs down a concentration gradient by a non-Na+-dependent process and that passive and facilitated diffusion mechanisms, the latter either by a high affinity-low capacity system or a low affinity-high capacity system, are involved in this transport. It also appears that gamma-glutamyltransferase and the gamma-glutamyl cycle are not involved in peptide absorption.
D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism*; D004151:Dipeptides / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D008815:Mice, Inbred Strains; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism*; D009842:Oligopeptides / Q000494:pharmacology; D010206:Papain / Q000494:pharmacology*
D000596:Amino Acids; D004151:Dipeptides; D009842:Oligopeptides; C015905:glycylleucine; D010206:Papain