Purines are synthesized using 5-phosphoribose (R-5-P) as the starting material step by step. Synthesis of GMP (Guanosine Monophosphate), IMP is converted to GMP in two enzymatic steps. De-novo synthesis of UMP (Uridine monophosphate). I. De-novo synthesis (synthesis from scratch): it is a biochemical pathway in which nucleotides are synthesized new from simple precursor molecules. Thus, de novo pathway of purine nucleotide synthesis refers to the process that utilizes small molecules such as ribose sugar, amino acids, CO 2, one carbon unit, etc. The pyrimidine pathway does not require ATP. Synthesis of Adenine and Guanine from IMP, @. Biosynthesis of pyrimidines is simple than that of purines. IMP is a branch point for the synthesis of the adenine and guanine nucleotides. During de novo biosynthesis, nucleotides … Understand the Two Pathways of nucleotide biosynthesis (1) De-novo synthesis and (2) Salvage Pathways. The recoveries of pyrimidines are catalyzed by the enzyme pyrimidine phosphoribosyltransferase which utilizes PRPP as the source of ribose-5-phsophate. Synthesis of Nucleoside Diphosphates and Triphosphates. C. the de novo synthesis of purine nucleotides. The rate of purine synthesis was gauged by the rate of incorporation of precursor (14C)formate into purines. CTP is synthesized by the amination of UTP by the enzyme CTP synthase. Overview of de novo purine biosynthesis (mainly in the liver and brain) 1. The first step is a replacement of … Step-9: Elimination of fumarate: Fumarate group is cleaved off from SACAIR to produce 5-aminoimidazole-4-carboxamide ribotide (AICAR) with the help of enzyme- adenylosuccinate lyase. Salvage pathways of purines and pyrimidines. Summary De novo purine synthesis is a biochemical pathway that creates purine nucleotides from simple molecules. Finally, purines and pyrimidines can be synthesized from smaller precursors ( de novo synthesis). The second phase of control is involved with maintaining an appropriate balance (not equality) between ATP and GTP. Step-4: Oxidation of dihydroorotate: Dihydroorotate is dehydrogenated to form orotate with the enzyme dihydroorotate dehydrogenase. How de-novo synthesis of purines & pyrimidines occurs? De novo (all over again) synthesis of purine nucleotides is synthesis of purines anew. @. Uridine monophosphate (UMP) also acts as the precursor of CTP and dTTP). Despite the es-sential functions of PDNS, salvage pathways recycle nucleotides to meet daily needs. It uses raw materials such as phosphoribose, amino acids … B. requires ATP uptake from the blood. Summary De novo purine synthesis is a biochemical pathway that creates purine nucleotides from simple molecules. Following diagram shows the source of different atoms in a pyrimidine skeleton identified by radio labeling studies. [ … This purine nucleotide synthesis pathway is associated with significantly less energy consumption than de novo synthesis. @. It also requires energy from ATP. This indirectly reduces the synthesis of purines & nucleic acids (DNA & RNA). The purine ring structure is built up one or a few atoms at a time, and is gradually attached to ribose phosphate throughout the process. Purine De Novo Synthesis Plants possess metabolic pathways for the de novo synthesis of purine nucleotides generating AMP, as well as pyrimidine nucleotides yielding UMP. Synthesis of Cytosine The pathway leading from IMP to AMP involves addition of amine from asparate and requires energy from GTP. Missed the LibreFest? Synthesis of deoxyribonucleotides Synthesis of Inosine monophosphate (IMP): (adsbygoogle=window.adsbygoogle||[]).push({}), Inosine monophosphate (IMP) is synthesized in 11 enzymatic steps from simple precursors as summarized below. Thus the purine synthesis starts with IMP synthesis (See the mind map). Synthesis of Uracil Enzymes that catalyze the de novo synthesis of purine nucleotides, which are needed in rapidly dividing cells, are known to assemble into loosely associated, multienzyme structures called purinosomes, but the extent to which these structures are metabolically active has been less certain. De novo synthesis of purines. 3. Step-3: Ring closure & dihydroorotate formation: By the elimination (condensation reaction) of one molecule of water, the carbamoyl aspartate is converted to a ring compound – dihydroorotate catalyzed by dihydroorotase enzyme. Free purine bases can be directly attached to PRPP to yield purine nucleotides. Synthesis of the first fully formed purine nucleotide, inosine monophosphate, IMP begins with 5′-phospho-α-ribosyl-1′-pyrophosphate, PRPP. Phosphorylated Nucleotides Subsequent reactions include adding glycine, adding carbon (from N 10-formyltetrahydrofolate), adding amine (from glutamine), closing of the first ring, addition of carboxyl (from \(\text{CO}_2\)), addition of aspartate, loss of fumarate (a net gain of an amine), addition of another carbon (from \(\text{N}_10\)-formyltetrahydrofolate), and closing of the second ring to form inosine monophosphate (IMP). De Novo Synthesis of Purine Nucleotides (IMP, AMP & GMP): i. Check back soon! Purine nucleotides produced from any of the input processes, including the de novo synthesis and salvage of either the endogenous or exogenous purines, could be converted into nucleotides of other purines. D. salvage of purine bases. Synthesis of Adenine and Guanine from IMP The image shows the source of different atoms in a purine skeleton identified by radio labeling studies, N1 is derived from amino group of Aspartate, N3 & N9 is derived from amide group of Glutamine, Aspartate, Formate, Glutamine, Glycine and Bicarbonate acts as the building blocks for purine synthesis. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. The reaction is catalyzed by PRPP synthetase. B. are synthesized de novo … Step-7: Acquisition of C6 atom of purine: An ATP dependent carboxylation reaction of 5-aminoimidazole ribotide (AIR) with HCO3- (bicarbonate) to produce carboxyaminoimidazole ribotide (CAIR) in the presence of enzyme AIR carboxylase. They inhibit the synthesis of purine nucleotides & nucleic acids. Purine salvage is favored over de novo synthesis, inasmuch as delivery of adenine to the muscle decreased (P < 0.005) de novo synthesis of AdN. Step-2: Eliminates fumarate group to form AMP: Adenylosuccinate is enzymatically converted to AMP by the removal of fumarate group with the help of enzyme adenylosuccinate lyase. Most purines are synthesized via salvage pathway while most pyrimidines are synthesized de novo. Question 1 of 16 Click on the single best answer. Providing ribose did not alter this preference of purine salvage pathway over de novo synthesis of AdN. De Novo Synthesis of Purine Nucleotides. (C6  of purine is contributed by HCO3-), Step-8: Acquisition of N1 atom of purine:  Aspartate is added and it forms an amide bond with C6 to form 5-aminoimidazole-4-(N-succinylocarboxamide) ribotide (SACAIR) in an ATP dependent reaction with the help of enzyme SAICAR synthetase (N1 of purine is contributed by aspartate). Both purines are derived from a precursor namely inosine-5′-monophosphate (IMP). Step-2: Synthesis of carbamoyl aspartate: Carbamoyl phosphate reacts with aspartate to yield carbamoyl aspartate catalyzed by the enzyme aspartate transcarbamoylase (ATCase). The de novo synthesis of purine nucleotides is identified by John Buchanan in 1948 using radiolabelling techniques. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. [ "article:topic", "purines", "authorname:ahern1", "showtoc:no", "license:ccbyncsa" ], 7.12: Deoxyribonucleotide de novo Biosynthesis. (C2 of purine ring is contributed by this N10-formyltetrahydrofolate), Step-11: Cyclization to form IMP: In the last reaction, the larger ring of FAICAR is enzymatically closed to forms Inosine Monophosphate (IMP) with the release of a water molecule catalyzed by the enzyme IMP cyclohydrolase, IMP does not accumulate in the cells rather it is rapidly converted into Adenine (as AMP) and Guanine (as GMP). Last Updated on January 9, 2020 by Sagar Aryal. to produce new purine nucleotides. Description: recycling of the purine bases adenine, guanine, and hypoxanthine; Substrate: PRPP with adenine or with guanine and hypoxanthine Turnover of nucleic acids (particularly RNA) in most cells releases adenine, guanine, and hypoxanthine. These free purines are reconverted to their corresponding nucleotides through salvage pathways. ADVERTISEMENTS: ii. There are 3 major steps are involved in this Purine synthesis pathway… C. are synthesized from ribonucleotides by an enzyme system involving thioredoxin. C. The pyrimidine pathway has more branches. Using 5-phosphoribosyl-1-pyrophosphate (PRPP), the de novo pathway enzymes build purine and pyrimidine nucleotides from “scratch” using simple molecules such as CO2, amino acids and tetrahydrofolate… The pathway from IMP to GMP involves an oxidation and addition of an amine from glutamine. @. Nucleotides contain Ribose or deoxyribose sugar One to three phosphate groups purine or pyrimidine hetercyclic nitrogen base. De novo purine nucleotide biosynthesis in yeast involves the 10-step production of the purine … Synthesis from amphibolic intermediates ( synthesis de novo ). Please Share with Your Friends... @. Step-5: Acquisition of the ribose phosphate moiety: Orotate reacts with PRPP to produce orotidine-5′-monophosphate (OMP) with the enzyme orotate phosphoribosyl transferase. (This reaction contribute N9 atom of purine form glutamine), Step-3: Acquisition of C4, C5 & N7 atoms of purine: Carboxylic group of glycine is combined with the amino group of β-5-phosphoribosylamine (PRA) to form glycinamide ribotide (GAR) with the help of enzyme – GAR synthetase (C4, C5, & N7 of purine are contributed by glycine), Step-4: Acquisition of C8 atom of purine: Amino group of glycinamide ribotide (GAR) is formylated with N10-formyltetrahydrofolate and forms  formylglycinamide ribotide (FGAR) with the presence of enzyme GAR transformylase. D. 5-Phosphoribosyl-1-pyrophosphate is required for the synthesis of (A) Purine nucleotides (B) Pyrimidine nucleotides (C) Both (A) and (B) (D) None of these. Purine nucleotide metabolism. These inhibitors also affect the proliferation of normally growing cells. The overall regulation of purine metabolism. In de novo pathways, the synthesis of nucleotides begins with their metabolic precursors: amino acids, ribose-5-phosphate, CO 2, and NH 3. 18. … Thus, the requirement to synthesize new purines in differentiated cells is small. Synthesis of IMP (precursor of Adenine and Guanine), @. De-novo synthesis of Pyrimidines (Uracil, Thymine & Cytosine). This complexity is due to the central role of nucleotides as energy currency, signaling molecules, and precursors to informational macromolecules in the cell. ADP can also be converted to ATP by various energy-releasing reactions in the cells such as by oxidative phosphorylation (electron transport system of respiration), by photophosphorylation (light reaction of photosynthesis) and also by substrate level phosphorylation (as in glycolysis), II. Enter your e-mail address. Thus three interacting pathways for nucleotides, nucleosides, and the free bases exist: salvage, degradation, … De novo purine nucleotide synthesis pathway. Salvage pathway (recycle pathway): used to recover bases and nucleosides formed during the degradation of RNA and DNA, @. PRPP amidotransferase is regulated partly by GMP and partly by AMP. In addition to incorporating atoms from glutamine, aspartate, and glycine, the de novo purine synthesis pathway combines molecules from other substrates, such as bicarbonate (HCO 3 −) and formyl-tetrahydrofolate (THF), with the activated ribose derived from the pentose phosphate pathway to form purine nucleotides (Figure 2A) (Lane and Fan, 2015, Villa et al., 2019). Problem 3 Deoxyribonucleotides A. cannot be synthesized so they must be supplied preformed in the diet. Control of the synthesis as a whole occurs at the amidotransferase step by nucleotide inhibition and/or [PRPP]. Purine nucleotides produced from any of the input processes, including the de novo synthesis and salvage of either the endogenous or exogenous purines, could be converted into nucleotides of other purines. 1. Thymine in the cell is synthesized as dTTP from dUMP by methylation in four steps. Nucleotide diphosphates are synthesized from corresponding nucleotide monophosphate by phosphate group transfer from ATP with the help of base specific nucleoside monophosphate kinase enzyme. Thus, de novo synthesis of purine nucleotides refers to the process that utilizes small molecules to produce purine nucleotides. Synthesis of Thymine Both are important molecules which are synthesized as nucleotides via both salvage and de novo pathways. The de novo purine synthesis pathway requires several moles of ATP for generation of each mole of purine nucleotide product, while HPRT and APRT require one ATP. Microbial sequences have been invaluable for the identification of 270 HOWARD ZALKIN AND JACK E. DIXON … Step-1: Donation of amino group by aspartate: Amino group of aspartate is enzymatically linked to the IMP (C6 of purine) coupled with GTP hydrolysis to form adenylosuccinate with the help of enzyme- adenylosuccinate synthetase. UMP is converted to UTP in two step kinase reaction with 2 molecules of ATP. In fact, whole-body rates of pyrimidine synthesis de novo in man as estimated by Weissman et al. De novo purine nucleotide synthesis occurs actively in the cytosol of the liver where all of the necessary enzymes are present as a macro-molecular aggregate. Adenine phosphoribosyltransferase (APRT) which mediates AMP formation using PRPP, 2. Synthesis of purine nucleotides by the de novo pathway begins with addition of a pyrophosphate to carbon 1 of ribose-5-phosphate, creating phosphoribosylpyrophosphate (PRPP). D e Novo Purine Nucleotide Synthesis in Vertebrates In this section, we summarize human chromosome localization for genes of de n o w purine nucleotide synthesis and describe strategies for cDNA cloning. TRANSPORT OF NUCLEOTIDES. Step-1: Ribose-5-phosphate activation and formation of PRPP): α-D-Ribose-phosphate (R5P) is activated with ATP to form 5-phosphoribosyl-α-pyrophosphate (PRPP) with the help of enzyme Ribose phosphate pyrophosphokinase. Purines can be generated in the cells during the degradation of nucleic acids through salvage pathways. Glucose-6-phosphate dehydrogenase deficiency. De-novo synthesis of UMP is completed in 6 enzymatic steps … The structural analogs of folic acid (e.g. Have questions or comments? If there is an imbalance of AMP or GMP, the enzyme is slowed, but not stopped, thus allowing the reactions leading to IMP to proceed, albeit slowly.  The salvage pathway is particularly important in certain tissues such as erythrocytes & brain where de novo (a new) synthesis of purine nucleotides is not operative. Eukaryotic cells have a heterogeneous cytoplasm, with compartments large and small, membrane bound or not. Step-10: Acquisition of C2 atom of purine: Amino group of AICAR react with N10-formyltetrahydrofolate (formylation) to form   5-formaminoimidazole-4-carboxamide ribotide (FAICAR) with presence of enzyme AICAR transformylase. The pathway leading to GMP is inhibited by its end product and the pathway to AMP is inhibited by its end product. Through a series of … Purines (adenine and guanine) are synthesized as ribo-nucleotides (nitrogen base + ribose sugar + phosphate) rather than as free bases. How de-novo synthesis of purines & pyrimidines occurs? When both nucleotides are in abundance, then PRPP amidotransferase is fully inhibited and the production of purines is stopped, thus preventing them from over-accumulating. How nucleotides are synthesized in the cells? Phosphoribosylation of purines. (In eukaryotes, dihydroorotate dehydrogenase is located in the outer surface of inner mitochondrial membrane. @. Apart from the primary role of DNA and RNA as “genetic information storage”, nucleotides also serves different functions in the cells such as energy carrier (ATP and GTP), components of co-enzymes (NAD and FAD) and cellular signal transduction (cAMP and cGMP as ‘second messengers’). The purine nucleotides of nucleic acids are adenosine 5-monophosphate (AMP; adenylate) and guanosine 5-monophosphate (GMP; guanylate), containing the purine bases adenine and guanine respectively. QUESTION 34 The de novo synthesis of pyrimidine nucleotides differs from the de novo synthesis of purine nucleotides in that: A. Dr. Kevin Ahern and Dr. Indira Rajagopal (Oregon State University). How nucleotides are synthesized in the cells? The effect of ribose 5-phosphate and 5-phosphoribosyl-1-pyrophosphate availability on de novo synthesis of purine nucleotides in rat liver slices. Purines and Pyrimidines Quiz. This can be contrasted against purine salvage, which recycles purines nucleotides after partial degradation. Please click on the Download Link / Button below to Save the post as a Single PDF file. (1) de-novo synthesis and (2) synthesis by salvage pathways. both de novo and salvage synthesis of purine and pyrimi- dine nucleotides as well as for the synthesis of NAD, histi- dine and tryptophan, any stress that alters PRPP availabil- Through a series of reactions utilizing ATP, tetrahydrofolate (THF) derivatives, glutamine, glycine and aspartate this pathway yields IMP. Purines are one of the two types of nitrogenous heterocyclic bases, which are one of the three components of the nucleotides that make up nucleic acids. R5P is then converted to its high energy, "activated" form, PRPP . De novo synthesis of purine nucleotides in human blood platelets. 2. The purine ring is synthesized along with the nucleotide i.e. Since the enzyme is not in the cytosol, the oxidizing power required for the conversion of dihydroorate is provided by Quinone). For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. Purines (Adenine & Guanine) and pyrimidines (Thymine, Cytosine & Uracil) are the two classes of nucleotides which forms the nucleic acids (DNA & RNA) in the cells. De novo purine synthesis refers to the biochemical pathway that creates purine nucleotides from simple molecules. Problem 3 Deoxyribonucleotides A. cannot be synthesized so they must be supplied preformed in the diet. Synthesis of Thymine (5-methyluracil) as dTTP: Thymine, which is present in DNA and not in RNA, is a methylated uracil residue. Purine and pyrimidine nucleotides can be synthesized in living organisms either by (i) de novo pathways, or (ii) salvage pathways. Salvage pathways of purines and pyrimidines, Purines (adenine and guanine) are synthesized as ribo-nucleotides (nitrogen base + ribose sugar + phosphate) rather than as free bases. Right click on the PDF and select ‘Save As‘ option to save the file to your computer. Feedback inhibition also controls the branched portion as GMP inhibits the conversion of IMP to XMP and AMP inhibits the conversion of IMP to adenylosuccinat… Thus three interacting pathways for nucleotides, nucleosides, and the free bases exist: salvage, degradation, and biosynthesis. N1, C6, C5 and C4 are derived from aspartate, Aspartate, Glutamine and bicarbonate contributes pyrimidine nucleus, (a). De novo purine synthesis … Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. 5-Nucleotidase converts nucleotides to purine _____, purine nucleoside phosphorlyase converts nucelosides to _____ Both reactions require PRPP to covert bases to nucleotides ... Allopurinol → Allopurinol ribose (HGPRTase) which inhibits PRPP aminotransferase and thus inhibits what de NOVO purine synthesis. Pentose phosphate pathway provides ribose for purine nucleotides, particularly for synthesis of purine nucleotides in T-cells, which are unable to salvage nucleotides from other pathways; Glucose-6-phosphate dehydrogenase is the committed step of the PPP - inhibited by negative feedback from NADPH . 2. Purine synthesis de novo was accelerated more than 13-fold in the leukocytes of two gouty patients affected with partial deficiency of hypoxanthine-guanine phosphoribosyltransferase, but was normal in the leukocytes of an obligate heterozygote for this enzyme abnormality. De novo synthesis of serine and glycine fuels purine nucleotide biosynthesis in human lung cancer tissues Nucleotide synthesis is essential to proliferating cells, but the preferred precursors for de novo biosynthesis are not defined in human cancer tissues. Inhibition of dihydroorotate dehydrogenase will inhibit pyrimidine synthesis in T lymphocytes, thereby it attenuate the autoimmune disease rheumatoid arthritis. Enzymes the in the formation of deoxyribonucleotides by the reduction of the corresponding ribonucleotides are called ribonucleotide reductases (RNRs). Boer P, Lipstein B, De Vries A, Sperling O. Legal. Step-2: Amidation of XMP: In the second step, XMP is amidated with the amide group from glutamine with the presence of H2O and hydrolysis of ATP yields GMP (Guanosine monophosphate); catalyzed by the enzyme GMP synthetase. De Novo Purine Synthesis Biochemistry - De Novo Nucleotide Synthesis D 12/30/2018 211 views 5.0 (4) Login to View Community Videos Login to View Community Videos Deoxyribonucleotides and Deoxythymidylate Synthesis … It is at this point that the significance of the unusual regulation of PRPP amidotransferase becomes apparent. Check back soon! B. are synthesized de novo using PRPP. Purine nucleotides are synthesized directly by the addition of a pyrophosphate at C-1 of the ribose sugar. (N3 of purine is contributed by glutamine). @. Synthesis of IMP begins with a reaction catalyzed by amidophosphoribosyltransferase (Ade4p) between PRPP (5-phosphoribosylpyrophosphate), … De novo purine nucleotide biosynthesis in yeast involves the 10-step production of the purine nucleotide inosine monophosphate (IMP), the common precursor to both adenosine monophosphate (AMP) and guanosine monophosphate (GMP). Synthesis of the first fully formed purine nucleotide, inosine monophosphate, IMP begins with 5′-phospho-α-ribosyl-1′-pyrophosphate, PRPP. 2. Synthesis of purine nucleotides differs fundamentally from that of pyrimidine nucleotides in that the bases are built on the ribose ring. Purine de novo synthesis (PDNS) represents a ba-sis for all other steps in nucleotide metabolism as well as all other interconnected pathways. Biochim … @. Purine-depleted medium or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT) treatment stimulates the purinosome assembly in HeLa cells. Both purines are derived from a precursor namely inosine-5′-monophosphate (IMP). Synthesis of IMP (precursor of Adenine and Guanine) This represents an important difference from pyrimidine synthesis … Moreover, pyrimidine synthesis is much simpler than purine synthesis. The PDF file will be opened in a new window in the browser itself. C. depends upon the action of nucleoside phosphorylase. This represents an important difference from pyrimidine synthesis (discussed later in this article), in which the ribose is added subsequently after the complete formation of the pyrimidine ring. Control of purine nucleotide synthesis has two phases. methotrexate), used to control cancer. Biosynthesis of pyrimidine nucleotides can occur by a de novo pathway or by the reutilization of preformed pyrimidine bases or ribonucleosides (salvage pathway). An ample supply of nucleotides in the cell is very essential for all the cellular processes. (C8 of purine is contributed by formate), Step-5: Acquisition of N3 atom of purine: Amide nitrogen of second glutamine is added to FGAR in an ATP-dependent reaction to form formylglycinamidine ribotide (FGAM) with the help of enzyme FGAM synthetase. D. salvage of purine bases. The starting material is ribose 5-phosphate, which is … 7.11: Purine de novo … Each one stimulates the synthesis of the other by providing the energy. ; The pyrimidine synthesis is a similar process than that of purines. Nucleotide biosynthesis in the cell can be grouped into two broad classes. The de novo pathway leading to the synthesis of AMP and GMP begins with the transfer of an amido group from glutamine to PRPP ().Since PRPP is used for the both de novo and salvage synthesis of purine and pyrimidine nucleotides as well as for the synthesis of NAD, histidine and tryptophan, any stress that alters PRPP availability affects multiple pathways. Substrates: CO2; glutamine; ATP; Aspartate; H2O; NAD+; Phosphoribosyl pyrophosphate (PRPP). Similar to purines, pyramidines are also recovered from the derivative intermediates of nucleic acids such as DNA and RNA. Purines and pyrimidines are two kinds of nitrogen-containing bases. Step-1: Synthesis of carbamoyl phosphate: With the hydrolysis of two ATP molecules, bicarbonate and amide nitrogen of glutamine combine to form carbamoyl phosphate in the presence of enzyme carbamoylphosphate synthetase II. Here, several metabolomic technologies were applied to quantify the static cellular levels of purine nucleotides and measure the de novo biosynthesis rate of IMP, AMP, and GMP. Purines are salvaged by two different enzymes in mammals: 1. (c). AMP differ from IMP in the replacement of its 6-keto group by an amino group whereas GMP differ from IMP in the presence of an amino group at C2, (a). Watch the recordings here on Youtube! For the participation of DNA and RNA synthesis, nucleoside monophosphates and diphosphates must be converted into nucleoside triphosphates. Step-6: Decarboxylation to form UMP: OMP undergoes decarboxylation with assistance of enzyme OMP decarboxylase (ODCase) to form uridine monophosphate (UMP). 1. De novo purine synthesis begins with the precursor molecule Ribose-5-phosphate (R5P) . Step-2: Acquisition of N9 atom of purine:  Amide nitrogen of glutamine displaces the pyrophosphate group of PRPP and it also inverts the configuration at C1′ to form β-5-phosphoribosylamine (PRA) with the help of enzyme amidophosphoribozyl transferase. Products: UTP; CTP; glutamate; NADH; CO2 In animals amino group is donated by glutamine whereas in bacteria, the amino group is donated directly by ammonia. 2. This post discuss the biosynthesis of Purines and Pyrimidines in an EASY but detailed way. De-novo synthesis of UMP (Uridine monophosphate) Uridine monophosphate (UMP) also acts as the precursor of CTP and dTTP). Similarly, nucleotide triphosphates are synthesized by the second round phosphorylation aided by ATP with the help of enzyme nucleoside diphosphate kinase. First step is a replacement of … C. the de novo pathways of in... 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