Transepithelial transport of the bioactive tripeptide, Val-Pro-Pro, in human intestinal Caco-2 cell monolayers.
Some of the food-derived tripeptides with angiotensin converting enzyme (ACE)-inhibitory activity have been reported to be hypotensive after being orally administered. The mechanism for the intestinal transport of these tripeptides was studied by using monolayer-cultured human intestinal Caco-2 cells which express many enterocyte-like functions including the peptide transporter (PepT1)-mediated transport system. Val-Pro-Pro, an ACE-inhibitory peptide from fermented milk, was used as a model tripeptide. A significant amount of intact Val-Pro-Pro was transported across the Caco-2 cell monolayer. This transport was hardly inhibited by a competitive substrate for PepT1. Since no intact Val-Pro-Pro was detected in the cells, Val-Pro-Pro apically taken by Caco-2 cells via PepT1 was likely to have been quickly hydrolyzed by intracellular peptidases, producing free Val and Pro. These findings suggest that PepT1-mediated transport was not involved in the transepithelial transport of intact Val-Pro-Pro. Paracellular diffusion is suggested to have been the main mechanism for the transport of intact Val-Pro-Pro across the Caco-2 cell monolayer.
Satake
Makoto
M
Department of Applied Biological Chemistry, The University of Tokyo, Japan.
Enjoh
Masashi
M
Nakamura
Yasunori
Y
Takano
Toshiaki
T
Kawamura
Yukio
Y
Arai
Soichi
S
Shimizu
Makoto
M
D001692:Biological Transport; D018938:Caco-2 Cells; D002851:Chromatography, High Pressure Liquid; D004705:Endocytosis / Q000187:drug effects; D004848:Epithelium / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D007413:Intestinal Mucosa / Q000378:metabolism*; D009842:Oligopeptides / Q000378:metabolism*
D009842:Oligopeptides