Savaiano D A, Clifford A J
J Nutr. 1981 Oct;111(10):1816-22. doi: 10.1093/jn/111.10.1816.
The capacity of rat intestinal epithelial cells for de novo purine synthesis and reutilization was studied in vitro with isolated cells and in vivo in functionally hepatectomized rats. De novo purine synthesis and purine reutilization were measured as the rate of incorporation of [14C]-glycine or [14C]-adenine, respectively, into the adenine and guanine pools of the intestinal cells. Isolated intestinal epithelial cells incubated with labeled purine or glycine incorporated only labeled adenine. Labeled glycine, guanine, hypoxanthine or xanthine were not incorporated into cellular adenine or guanine. Labeled glycine, given intravenously to functionally hepatectomized rats, was not incorporated into the adenine and guanine of intestinal villus or crypt cells. Labeled glycine was readily incorporated into hepatic adenine and guanine pools of a sham-operated rat. The failure of glycine to be incorporated into intestinal cells in vitro or in vivo demonstrated that these cells lack de novo purine synthesis. Since adenine was readily incorporated into the adenine pool of these cells, we believe that adenine, which is synthesized in the liver or supplied in the diet, was an important precursor for the nucleic acid synthesis in this study.
采用分离的细胞在体外以及在功能性肝切除的大鼠体内研究了大鼠肠上皮细胞从头合成嘌呤和再利用嘌呤的能力。分别以[14C] - 甘氨酸或[14C] - 腺嘌呤掺入肠细胞腺嘌呤和鸟嘌呤池的速率来测定从头嘌呤合成和嘌呤再利用。用标记的嘌呤或甘氨酸孵育分离的肠上皮细胞，仅掺入标记的腺嘌呤。标记的甘氨酸、鸟嘌呤、次黄嘌呤或黄嘌呤未掺入细胞的腺嘌呤或鸟嘌呤中。给功能性肝切除的大鼠静脉注射标记的甘氨酸，未掺入肠绒毛或隐窝细胞的腺嘌呤和鸟嘌呤中。标记的甘氨酸很容易掺入假手术大鼠的肝脏腺嘌呤和鸟嘌呤池中。甘氨酸在体外或体内均未能掺入肠细胞，这表明这些细胞缺乏从头嘌呤合成能力。由于腺嘌呤很容易掺入这些细胞的腺嘌呤池中，我们认为在肝脏中合成或由饮食提供的腺嘌呤是本研究中核酸合成的重要前体。
