Dietary nucleotides: A conditional requirement

摘要: Purines and pyrimidines, either as nucleobases or polymeric nucleic acids, are not deemed to be essential because de novo synthetic pathways present for synthesis of these molecules. However, a growing body evidence suggests that acids and/or the corresponding purine pyrimidine bases conditionally required normal responses specific organs systems body. The conditions expose this heretofore recognized requirement dietary nucleotides those under which there is rapid cell replication. Endogenous purines pyrimidines synthesized from amino other glycine, glutamine, asparate, CO2 formate, while asparate NH3, C02. Both ribosylated form nucleosides; compounds phosphorylated via PRPP nucleotides. These can converted dior triphosphates, degraded nucleosides intracellularly. After removal ribose (or deoxyribose) moiety, nucleobase uracil cytosine, hypoxanthine, further catabolized. Alternately, salvaged use substrate 5 monophosphate by phosphoribosyltranferases in cell.’ Previous studies on fate suggested limited oral bioavailability compared with similar parenteral dose.’ gut has adenine capacity, largely extracted at level gut. More recent suggest more profound influence organism whole. LopezNavarro et al.3 demonstrated rodents fed nucleotidefree diet showed significant early decrease hepatic levels nucleotides, group supplemented no such change. This biochemical perturbation was associated persistent RNA content rats nucleotide-free diet. In contrast, maintained content. exogenous greater Lopez-Navarro documented nucleotide much vulnerable restriction. Supplementation failed return totally normal, although may have been due an inadequate provision dose Further confirmation critical role reflected study labeling hens mice C-labeled algae. Dietary were significantly incorporated into pools, virtually used acid synthesis.5 Moreover, uracil, but contributed nucleoside synthesis. authors concluded base nucleosides, nutrients. nutrition experiments described above imply changes pools will result suboptimal nucleotide-deprived hosts. experimental models document consequences diet-induced test three host responses: regeneration following resection injury; maturation response hostspecific nonspecific immune responses. Following 70% resection, regimen containing 10% nitrogen enhanced regeneration.6 Hepatic injury galactosamine administration reduced nucleotide/nucleoside mixture.’ findings supply ribosomal controls proliferative chemical affected availability it appears critical, since substrates correlate best Another rapidly proliferating pool restriction small intestinal animals deprived nucleobases.’ true presence absence protein Furthermore, appeared