Characteristics and mechanism of glutamine-dipeptide absorption in human intestine.
Characteristics and mechanism of glutamine-dipeptide absorption in human intestine.
复制标题
谷氨酰胺二肽在人体肠道吸收的特性及机制。
DOI：
10.1016/0016-5085(92)91088-l
复制
发表时间：
1992
期刊：
影响因子：
29.4
通讯作者：
Adibi,SA
中科院分区：
文献类型：
--
作者：
Minami,H;Morse,EL;Adibi,SA
利用体内和体外技术，研究了人体肠粘膜从管腔寡肽中获得谷氨酰胺的机制。由粘膜刷状缘膜的水解率是三倍以上的丙氨酰谷氨酰胺比甘氨酰谷氨酰胺。尽管存在这种差异，但在肠灌注过程中，含有甘氨酰谷氨酰胺的试验溶液中二肽和氨基酸的消失率高于丙氨酰谷氨酰胺。此外，在输注两种二肽期间，水解产物的管腔内出现率相似，并且小于母体二肽的消失率的5%。相反，游离谷氨酰胺，肽结合谷氨酰胺的刷状缘膜囊泡的摄取不抑制删除钠或添加游离氨基酸的孵育介质，但抑制其他寡肽和刺激的质子梯度。囊泡对甘氨酰谷氨酰胺和丙氨酰谷氨酰胺的饱和摄取的抑制常数没有显著差异，表明肽转运蛋白具有相似的亲和力。结果表明，谷氨酰胺二肽在人体肠道中的主要吸收机制是吸收为完整的二肽，而不是水解。
Using in vivo and in vitro techniques, the mechanism by which intestinal mucosa obtains glutamine from luminal oligopeptides was investigated in humans. The rate of hydrolysis by mucosal brush border membrane was more than threefold greater for alanylglutamine than for glycylglutamine. Despite this difference, rates of dipeptide and amino acid disappearance during intestinal perfusion were greater from test solutions containing glycylglutamine than alanylglutamine. Furthermore, rates of intraluminal appearance of products of hydrolysis during the infusion of two dipeptides were similar and < 5% of the disappearance rate of the parent dipeptide. In contrast to free glutamine, uptake of peptide-bound glutamine by brush border membrane vesicles was not inhibited by deletion of sodium or addition of free amino acids to the incubation medium but was inhibited by other oligopeptides and stimulated by a proton gradient. Inhibition constants for the saturable uptake of glycylglutamine and alanylglutamine by vesicles were not significantly different, suggesting similar affinities for the peptide transporter. It is concluded that in human intestine the predominant mechanism for assimilation of glutamine-dipeptides is absorption as intact dipeptide rather than hydrolysis.