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Pyrimidines
Published in Mihai V. Putz, New Frontiers in Nanochemistry, 2020
Nicoleta A. Dudaş, Mihai V. Putz
In the pyrimidine ring, C2 comes from HCO3− (CO2), N3 comes from glutamine, and the remainder of the pyrimidine molecule (C4-C5-C6-N1) comes from a molecule of aspartate. Step 1 of pyrimidine de novo biosynthesis required two adenosine triphosphate (ATP), and involves formation of carbamoyl phosphate (Figure 41.8) (Löffler & Zameitat, 2004, 2013; Grande-García et al., 2014; Kafer et al., 2004; Rider, L. W. 2009, Schröder et al., 2005; Witz et al., 2012). This step is catalyzed by cytosolic enzyme, carbamoyl phosphate synthetase II (CPS-II), which is different from carbamoylphosphate synthetase I (CPS I) found in mitochondria and used for the urea cycle in mammalian liver, thus CPS II is the first step committed to pyrimidine metabolism in higher animals, PRPP and ATP activate the enzyme and UDP (uridine-5-diphosphate), and UTP (uridine-5-triphosphate) are allosteric inhibitors of its activity (Hermansen et al., 2015; Löffler & Zameitat, 2004, 2013; Grande-García et al., 2014; Rider, 2009; Kafer et al., 2004; Schröder et al., 2005; Witz et al., 2012). Step 2 leads to the formation of N-carbamoyl aspartate (catalyzed by ATCase), and is the committed step for pyrimidine synthesis in prokaryotes. In step 3, the pyrimidine ring is cyclized by DHOase. In step 4, from dihydroorotate is formatting the orotate, process catalyzed by DHODHase. In step 5, OPRTase catalyze the reaction between orotate and PRPP to form orotidine-5-phosphate (OMP). In step 6, catalyzed by OMP decarboxylase, OMP is decarboxylated to form uridine-5′-monophosphate (UMP) (Figure 41.8) (Hermansen et al., 2015; Löffler & Zameitat, 2004, 2013; Grande-García et al., 2014; Rider, 2009; Kafer et al., 2004; Schröder et al., 2005; Witz et al., 2012).
Hepatic proteomic assessment of oral ingestion of titanium dioxide nano fiber (TDNF) in Sprague Dawley rats
Published in Journal of Environmental Science and Health, Part A, 2022
Worlanyo E. Gato, Ji Wu, Isaac Appiah, Olivia Smith, Haresh Rochani
To explore the effects of TDNF ingestion in Sprague Dawley rats, a proteomics approach was used. Proteomics is a useful tool to evaluating the complete structure and function of proteins in an organism.[22] More than 400 hundred proteins were identified to be involved in TDNF effects in the liver. Some of these include Acyl-coenzyme A synthetase ACSM2, mitochondrial (Accession#: O70490), Betaine–homocysteine S-methyltransferase 1 (Accession#: O09171), Acyl-CoA dehydrogenase family member 11 (Accession#: B3DMA2) and Ornithine transcarbamylase, mitochondrial precursor (Accession#: P00481) among many more. These proteins are involved in such processes as catalysis of fatty acids by CoA, homocysteine metabolism, beta oxidation and the condensation of carbamoyl phosphate in the urea cycle.[23–25]
Diazinon impairs bioenergetics and induces membrane permeability transition on mitochondria isolated from rat liver
Published in Journal of Toxicology and Environmental Health, Part A, 2020
Camila Araújo Miranda, Anilda Rufino de Jesus Santos Guimarães, Paulo Francisco Veiga Bizerra, Fábio Erminio Mingatto
It is also well-established that liver is a target tissue of DZN that exhibits liver dysfunction, with increase of serum activities of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and γ-glutamyl transferase (Abdel-Daim et al. 2016; El-Shenawy et al. 2010), decrease in the activity of fumarylacetoacetase, carbamoyl-phosphate synthase and S-adenosylmethionine synthetase (Lari et al. 2014), genotoxic effects (Ezzi et al. 2016), free radical production (Messarah et al. 2013), antioxidant depletion and oxidative stress induction (Abdel-Daim et al. 2019; Naji, Heidarian, and Samani 2017). However, the mechanism of toxic action of this pesticide on liver has not been fully described.
Biosorption of cyanate by two strains of Chlamydomonas reinhardtii: evaluation of the removal efficiency and antioxidants activity
Published in International Journal of Phytoremediation, 2021
Mostafa M. S. Ismaiel, Yassin M. El-Ayouty, Asmaa H. Al-Badwy
Cyanide and its derivatives are naturally generated in the cellular process as that of urea and carbamoyl phosphate metabolism (Guilloton and Karst 1987). Cyanate itself is less toxic than cyanide derivatives which may result from the photochemical oxidation of cyanide (Nowakowska et al. 2006). In this regards, Luque-Almagro et al. (2016) showed the possible degradation of cyanide and nitriles into ammonia and carboxylic derivatives through the hydrolytic reactions. For instance, cyanidase and cyanase hydratase act on HCN forming formic acid or formamide which converted into ammonia and carboxylic acid in one step (Gupta et al. 2010; Cabello et al. 2018).