EVIDENCE FOR 2 DIFFERENT MODES OF TRIPEPTIDE DISAPPEARANCE IN HUMAN INTESTINE - UPTAKE BY PEPTIDE CARRIER SYSTEMS AND HYDROLYSIS BY PEPTIDE HYDROLASES
EVIDENCE FOR 2 DIFFERENT MODES OF TRIPEPTIDE DISAPPEARANCE IN HUMAN INTESTINE - UPTAKE BY PEPTIDE CARRIER SYSTEMS AND HYDROLYSIS BY PEPTIDE HYDROLASES
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DOI：
10.1172/jci108215
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发表时间：
1975-01-01
影响因子：
15.9
通讯作者：
AMIN, PM
中科院分区：
文献类型：
--
作者：
ADIBI, SA;MORSE, EL;AMIN, PM
两种三肽（三甘氨酸和三亮氨酸）在溶解度和分子量方面显着不同，已通过健康人类志愿者的空肠灌注研究了其在肠道中的命运。从含有三甘氨酸或三亮氨酸的测试溶液中摄取甘氨酸或亮氨酸的速率分别大于从含有相应量的游离甘氨酸或游离亮氨酸的测试溶液中摄取的速率。 100 mM 三甘氨酸溶液中甘氨酸的摄取速率高于 150 mM 二甘氨酸溶液中的甘氨酸摄取速率。每次输注三甘氨酸负荷（例如 1,000 微摩尔/分钟）时，三甘氨酸消失 (810 +/- 40) 或甘氨酸吸收 (2,208 +/- 122) 的速率（微摩尔/分钟/30 厘米）明显大于二甘氨酸 (56 +/- 10) 或游离甘氨酸 (110 +/- 18) 的管腔累积速率。输注 5 mM 三亮氨酸溶液期间游离亮氨酸的管腔累积速率比输注 5 mM 三甘氨酸溶液期间游离甘氨酸的管腔累积速率高出三倍以上。管腔液没有表现出针对三甘氨酸的水解活性，但含有一些针对三亮氨酸的活性。大负载亮氨酸的游离氨基酸载体系统的饱和不影响三甘氨酸测试溶液中甘氨酸的吸收率，但异亮氨酸显着抑制三亮氨酸溶液中的吸收。当二肽载体系统被大量甘氨酰亮氨酸饱和时，三甘氨酸的消失率显着降低，而三亮氨酸的消失率不受影响。向三肽溶液中添加甘氨酰亮氨酸后，二甘氨酸的管腔积累量略有增加，而二亮氨酸积累量增加了 62 倍。
The intestinal fate of two tripeptides (triglycine and trileucine), which differ markedly in solubility and molecular weight, have been investigated by jejunal perfusion in healthy human volunteers. Rates of glycine or leucine uptake from test solutions containing triglycine or trileucine were greater than from test solutions containing corresponding amounts of free glycine or free leucine, respectively. The rate of glycine uptake from a 100 mM triglycine solution was greater than that from a 150 mM diglycine solution. At each infused load of triglycine (e.g., 1,000 mumol/min) the rates (micromoles/minutes per 30 cm) of either triglycine disappearance (810 +/- 40) or glycine absorption (2,208 +/- 122) were markedly greater than the luminal accumulation rates of either diglycine (56 +/- 10) or free glycine (110 +/- 18). The luminal accumulation rate of free leucine during infusion of a 5 mM trileucine solution was over threefold greater than that of free glycine during the infusion of a 5 mM triglycine solution. Luminal fluid exhibited no hydrolytic activity against triglycine, but contained some activity against trileucine. Saturation of free amino acid carrier system with a large load of leucine did not affect glycine absorption rate from a triglycine test solution, but isoleucine markedly inhibited the uptake from a trileucine solution. When the carrier system for dipeptides was saturated with a large amount of glycylleucine, the disappearance rate of triglycine was considerably reduced while that of trileucine remained unaffected. After addition of glycylleucine to tripeptide solutions, there was a minimal increase in the luminal accumulation of diglycine, while dileucine accumulation was incresed by 62-fold.