Magni Giulio, Orsomando Giuseppe, Raffelli Nadia, Ruggieri Silverio
Istituto di Biotecnologie Biochimiche, Universita Politecnica delle Marche, Via Ranieri 69, 60131 Ancona, Italy.
Front Biosci. 2008 May 1;13:6135-54. doi: 10.2741/3143.
Mounting evidence attests to the paramount importance of the non-redox NAD functions. Indeed, NAD homeostasis is related to the free radicals-mediated production of reactive oxygen species responsible for irreversible cellular damage in infectious disease, diabetes, inflammatory syndromes, neurodegeneration and cancer. Because the cellular redox status depends on both the absolute concentration of pyridine dinucleotides and their respective ratios of oxidized and reduced forms (i.e., NAD/NADH and NADP/NADPH), it is conceivable that an altered regulation of the synthesis and degradation of NAD impairs the cell redox state and likely contributes to the mechanisms underlying the pathogenesis of the above mentioned diseases. Taking into account the recent appearance in the literature of comprehensive reviews covering different aspects of the significance of NAD metabolism, with particular attention to the enzymes involved in NAD cleavage, this monograph includes the most recent results on NAD biosynthesis in mammals and humans. Due to recent findings on nicotinamide riboside as a nutrient, its inclusion under "niacins" is proposed. Here, the enzymes involved in the de novo and reutilization pathways are overviewed.
越来越多的证据证明了非氧化还原型NAD功能的至关重要性。事实上，NAD稳态与自由基介导的活性氧生成有关，而活性氧会导致传染病、糖尿病、炎症综合征、神经退行性变和癌症中细胞的不可逆损伤。由于细胞氧化还原状态取决于吡啶二核苷酸的绝对浓度及其氧化态与还原态的各自比例（即NAD/NADH和NADP/NADPH），因此可以想象，NAD合成与降解的调节改变会损害细胞氧化还原状态，并可能促成上述疾病发病机制的潜在机制。考虑到最近文献中出现了涵盖NAD代谢重要性不同方面的综合综述，尤其关注参与NAD裂解的酶，本专著收录了哺乳动物和人类中NAD生物合成的最新研究结果。鉴于最近关于烟酰胺核糖作为一种营养素的发现，建议将其归入“烟酸”类别。在此，对从头合成途径和再利用途径中涉及的酶进行了概述。
