Blachier F, Darcy-Vrillon B, Sener A, Duée P H, Malaisse W J
Laboratory of Experimental Medicine, Brussels Free University, Belgium.
Biochim Biophys Acta. 1991 May 17;1092(3):304-10. doi: 10.1016/s0167-4889(97)90005-7.
Rat enterocytes exposed to L-arginine in the absence of any other exogenous substrate were found to actively metabolize this cationic amino acid. L-Arginine was converted to L-citrulline either directly in a NADPH-sensitive manner thought to be coupled with the generation of NO, or indirectly through the sequence of reactions catalyzed by arginase and ornithine transcarbamylase. A large fraction of L-citrulline and L-ornithine generated from exogenous L-arginine was released in the incubation medium. The production of CO2 and (poly)amines from L-arginine occurred at rates 2 to 3 orders of magnitude lower than that characterizing the net uptake of the cationic amino acid, and this despite the fact that enterocytes were equipped to allow the interconversion of L-ornithine and L-glutamate. It is concluded that the oxidative catabolism of L-arginine in enterocytes is quantitatively negligible relative to its conversion to L-citrulline and L-ornithine.
在没有任何其他外源性底物的情况下，暴露于L-精氨酸的大鼠肠上皮细胞被发现可积极代谢这种阳离子氨基酸。L-精氨酸以对NADPH敏感的方式直接转化为L-瓜氨酸，这种方式被认为与一氧化氮的生成有关，或者通过精氨酸酶和鸟氨酸转氨甲酰酶催化的反应序列间接转化。由外源性L-精氨酸产生的大部分L-瓜氨酸和L-鸟氨酸被释放到孵育培养基中。L-精氨酸产生二氧化碳和（多）胺的速率比阳离子氨基酸的净摄取速率低2至3个数量级，尽管肠上皮细胞具备使L-鸟氨酸和L-谷氨酸相互转化的能力。得出的结论是，相对于其转化为L-瓜氨酸和L-鸟氨酸，肠上皮细胞中L-精氨酸的氧化分解在数量上可忽略不计。
