LaFon S W, Nelson D J
Mol Biochem Parasitol. 1985 Jan;14(1):11-22. doi: 10.1016/0166-6851(85)90101-x.
Intact Eimeria tenella sporozoites and merozoites did not incorporate radiolabeled formate or glycine into their purine nucleotides suggesting a lack of de novo purine synthesis. However, [U-14C]glucose was incorporated into the cellular purine and pyrimidine nucleotide pools of both forms probably via conversion to radiolabeled ribose-1-phosphate and/or 5'-phosphoribosyl-1-alpha-pyrophosphate and the resulting action of various purine and pyrimidine salvage enzymes. Both forms of the parasite salvaged radiolabeled purine bases and nucleosides in a similar fashion. These purines were incorporated into ribonucleotides and into RNA and DNA. Adenine and inosine were transformed to hypoxanthine. Adenosine was converted to both inosine and hypoxanthine. Hypoxanthine and xanthine were not oxidized to uric acid but were metabolized to nucleotides. Guanosine was cleaved to guanine; guanine was deaminated to xanthine. The results demonstrate the presence of several purine salvage pathways. Purine phosphoribosylating and nucleoside phosphorylating activities as well as purine nucleoside cleaving and adenosine, adenine and guanine deaminating activities were evident. The metabolic evidence suggests the enzymes required to convert the newly formed nucleoside monophosphates to ATP and GTP were present also.
完整的柔嫩艾美耳球虫子孢子和裂殖子不能将放射性标记的甲酸或甘氨酸掺入其嘌呤核苷酸中，这表明缺乏嘌呤的从头合成。然而，[U-14C]葡萄糖可能通过转化为放射性标记的核糖-1-磷酸和/或5'-磷酸核糖-1-α-焦磷酸以及各种嘌呤和嘧啶补救酶的作用，被掺入这两种形式的细胞嘌呤和嘧啶核苷酸池中。该寄生虫的两种形式以相似的方式挽救放射性标记的嘌呤碱基和核苷。这些嘌呤被掺入核糖核苷酸以及RNA和DNA中。腺嘌呤和次黄嘌呤被转化为次黄嘌呤。腺苷被转化为次黄嘌呤和肌苷。次黄嘌呤和黄嘌呤没有被氧化为尿酸，而是被代谢为核苷酸。鸟苷被裂解为鸟嘌呤；鸟嘌呤脱氨基为黄嘌呤。结果表明存在几种嘌呤补救途径。嘌呤磷酸核糖基化和核苷磷酸化活性以及嘌呤核苷裂解和腺苷、腺嘌呤和鸟嘌呤脱氨基活性很明显。代谢证据表明也存在将新形成的核苷单磷酸转化为ATP和GTP所需的酶。
