The transamination of glutamic and aspartic acids during absorption by the small intestine of the dog in vivo
The transamination of glutamic and aspartic acids during absorption by the small intestine of the dog in vivo
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狗体内谷氨酸和天冬氨酸在小肠吸收过程中的转氨作用
DOI：
10.1113/jphysiol.1957.sp005722
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发表时间：
1957
期刊：
影响因子：
--
通讯作者：
G. Wiseman
中科院分区：
文献类型：
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作者：
K. D. Neame;G. Wiseman
1949 年，Dent 和 Schilling 重新研究了摄入蛋白质的命运，他们得出的结论是，异源蛋白质几乎完全以游离氨基酸的形式被吸收，并且食用酪蛋白后门静脉血中氨基酸的浓度很大程度上与人们根据该蛋白质的氨基酸含量所期望的浓度相同。然而，谷氨酸的特殊之处在于，鉴于酪蛋白的谷氨酸含量高，其在门静脉血中的浓度远低于预期。 1953年，怀斯曼研究了大鼠离体小肠逆浓度梯度转运各种氨基酸的能力，发现虽然L型丙氨酸、苯丙氨酸、蛋氨酸、组氨酸和异亮氨酸逆浓度梯度被吸收，但谷氨酸和天冬氨酸则不然。他还发现部分谷氨酸和天冬氨酸从整个实验系统中消失。 Matthews & Wiseman (1953) 使用体外技术 (Wiseman, 1953)，随后表明，当将谷氨酸或天冬氨酸引入肠腔时，丙氨酸会出现在浸润肠浆膜表面的液体中。他们得出结论，转氨作用发生在谷氨酸或天冬氨酸的吸收过程中，并导致门静脉血中出现丙氨酸。以下实验在体内研究了这一过程，证实了他们的假设，并给出了这些氨基酸在狗小肠吸收过程中之间的定量关系。
The fate of ingested protein was re-investigated by Dent & Schilling in 1949, and they concluded that heterologous protein is absorbed almost entirely as free amino acids and that the concentration of the amino acids in the portal blood after eating casein is largely what one would expect from a knowledge of the amino acid content of that protein. Glutamic acid, however, is exceptional in that its concentration in the portal blood is much lower than would be expected in view of the high glutamic acid content of casein. In 1953 Wiseman investigated the ability of the isolated small intestine of the rat to transport various amino acids against a concentration gradient, and found that although the L-forms of alanine, phenylalanine, methionine, histidine and isoleucine are absorbed against a concentration gradient, those of glutamic and aspartic acids are not. He also found that part of the glutamic and aspartic acids disappears from the experimental system as a whole. Matthews & Wiseman (1953), using an in vitro technique (Wiseman, 1953), then showed that when either glutamic acid or aspartic acid is introduced into the intestinal lumen, alanine appears in the fluid bathing the serosal surface of the intestine. They concluded that transamination occurs during the absorption of glutamic or aspartic acid and results in the appearance of alanine in the portal blood. The following experiments, investigating this process in vivo, confirm their hypothesis, and also give the quantitative relationship between these amino acids during absorption from the dog's small intestine.