Ipata Piero L, Pesi Rossana
Department of Biology, Unit of Biochemistry, University of Pisa, Pisa, Italy
Department of Biology, Unit of Biochemistry, University of Pisa, Pisa, Italy.
Adv Physiol Educ. 2017 Jun 1;41(2):286-290. doi: 10.1152/advan.00180.2016.
It is well known that a strong metabolic interrelationship exists between ureagenesis and gluconeogenesis. In this paper, we present a detailed, overall equation, describing a possible metabolic link between ureagenesis and gluconeogenesis. We adopted a guided approach in which we strongly suggest that students, when faced with the problem of obtaining the overall equation of a metabolic pathway, carefully account for all atoms and charges of the single reactions, as well as the cellular localizations of the substrates, and the related transport systems. If this suggestion is always taken into account, a balanced, overall equation of a metabolic pathway will be obtained, which strongly facilitates the discussion of its physiological role. Unfortunately, textbooks often report unbalanced overall equations of metabolic pathways, including ureagenesis and gluconeogenesis. Most likely the reason is that metabolism and enzymology have been neglected for about three decades, owing to the remarkable advances of molecular biology and molecular genetics. In this paper, we strongly suggest that students, when faced with the problem of obtaining the overall reaction of a metabolic pathway, carefully control if the single reactions are properly balanced for atoms and charges. Following this suggestion, we were able to obtain an overall equation describing the metabolic interrelationship between ureagenesis and gluconeogenesis, in which urea and glucose are the final products. The aim is to better rationalize this topic and to convince students and teachers that metabolism is an important and rewarding chapter of human physiology.
众所周知，尿素生成与糖异生之间存在着紧密的代谢相互关系。在本文中，我们给出了一个详细的总反应式，描述了尿素生成与糖异生之间可能的代谢联系。我们采用了一种引导式方法，强烈建议学生在面对推导代谢途径总反应式的问题时，仔细考虑单个反应中的所有原子和电荷，以及底物的细胞定位和相关的转运系统。如果始终考虑这一建议，就会得到一个平衡的代谢途径总反应式，这将极大地促进对其生理作用的讨论。不幸的是，教科书经常给出代谢途径（包括尿素生成和糖异生）的不平衡总反应式。最有可能的原因是，由于分子生物学和分子遗传学的显著进展，代谢和酶学在大约三十年里一直被忽视。在本文中，我们强烈建议学生在面对推导代谢途径总反应的问题时，仔细检查单个反应的原子和电荷是否正确平衡。遵循这一建议，我们得以获得一个描述尿素生成与糖异生之间代谢相互关系的总反应式，其中尿素和葡萄糖是最终产物。目的是更好地理清这一主题，并让学生和教师相信，代谢是人体生理学中一个重要且有价值的章节。
