Amino acid metabolism and the energetics of growth.
Amino acid metabolism and the energetics of growth.
复制标题
氨基酸代谢和生长能量学。
DOI：
10.1080/17450399809381918
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Stoll,B
中科院分区：
文献类型：
--
作者：
Reeds,PJ;Burrin,DG;Davis,TA;Stoll,B
非必需氨基酸参与了大量与蛋白质合成没有直接关系的功能。最近使用跨器官平衡和稳定同位素示踪剂组合的研究表明，谷氨酸、谷氨酰胺、甘氨酸和半胱氨酸的内脏外通量的很大一部分来自组织合成。在这方面，一个关键的氨基酸是谷氨酸。饮食来源的谷氨酸在小肠粘膜中几乎没有代谢。此外，由于谷氨酸是唯一可以由哺乳动物通过酮酸的还原胺化合成的氨基酸，因此它是合成其他非必需氨基酸的最终氮供体。由于谷氨酸及其产物谷氨酰胺的合成涉及三磷酸腺苷（ATP）的消耗，因此非必需氨基酸的合成可能对蛋白质合成的能量学以及蛋白质沉积具有重要意义。本文讨论了蛋白质沉积的能量消耗问题，考虑了氨基酸氧化和非必需氨基酸合成的代谢生理，并试图联合收割机推测氨基酸代谢对动物能量交换的总体影响。
The nonessential amino acids are involved in a large number of functions that are not directly associated with protein synthesis. Recent studies using a combination of transorgan balance and stable isotopic tracers have demonstrated that a substantial portion of the extra‐splanchnic flux of glutamate, glutamine, glycine and cysteine derives from tissue synthesis. A key amino acid in this respect is glutamic acid. Little glutamic acid of dietary origin escapes metabolism in the small intestinal mucosa. Furthermore, because glutamic acid is the only amino acid that can be synthesized by mammals by reductive amination of a ketoacid, it is the ultimate nitrogen donor for the synthesis of other nonessential amino acids. Because the synthesis of glutamic acid and its product glutamine involve the expenditure of adenosine triphosphate (ATP), it seems possible that nonessential amino acid synthesis might have a significant bearing on the energetics of protein synthesis and, hence, of protein deposition. This paper discusses the topic of the energy cost of protein deposition, considers the metabolic physiology of amino acid oxidation and nonessential amino acid synthesis, and attempts to combine the information to speculate on the overall impact of amino acid metabolism on the energy exchanges of animals.