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人的红细胞不能合成嘌呤,但可通过摄入现成的嘌呤硷(如次黄嘌呤、鸟嘌呤和腺嘌呤)以满足它们合成嘌呤核苷酸的需要。在放射性嘌呤硷掺入红细胞的研究中,嘌呤硷在生理浓度时,细胞内几乎没有测出标记的自由硷。仅仅观察到加入硷的单核苷酸、二核苷酸和三核苷酸。两种嘌呤磷酸核糖转移酶(嘌呤-PRTs)是使嘌呤硷进入细胞的酶。在磷酸核糖焦磷酸(PRPP)存在时,次黄嘌呤-鸟嘌呤磷酸核糖转移酶(HG-PRT)催化次黄嘌呤和鸟嘌呤分别转变为IMP和GMP。在PRPP存在时腺嘌呤磷酸核糖转移酶(A-PRT)催化腺嘌呤转变为AMP。现已证明,嘌呤硷可借助中间载体转移到哺乳动物的细胞中。
Human erythrocytes do not synthesize purines, but they can meet the need for their synthesis of purine nucleotides by ingesting ready-made purine guanidines (such as hypoxanthine, guanine, and adenine). In the study of the incorporation of radioactive purine into red blood cells, free labeled ticks were rarely detected in cells at physiological concentrations. Only mononucleotide, dinucleotide and trinucleotide were added to the quinone. Two purine phosphoribosyl transferases (purine-PRTs) are enzymes that allow purine quinones to enter cells. In the presence of phosphoribosyl pyrophosphate (PRPP), hypoxanthine-guanine phosphoribosyltransferase (HG-PRT) catalyzes the conversion of hypoxanthine and guanine to IMP and GMP, respectively. Adenine phosphoribosyl transferase (A-PRT) catalyzes the conversion of adenine to AMP in the presence of PRPP. It has been demonstrated that purine quinones can be transferred to mammalian cells by means of intermediate vectors.