Nucleotide metabolism

From WikiMD's Wellness Encyclopedia

Nucleotide metabolism is a fundamental aspect of biochemistry and cell biology involving the synthesis, breakdown, and regulation of nucleotides. Nucleotides, the building blocks of DNA and RNA, play critical roles in cellular processes such as genetic information storage, protein synthesis, and energy transfer. This article provides an overview of the pathways involved in nucleotide metabolism, including de novo synthesis, salvage pathways, and nucleotide degradation.

De Novo Synthesis[edit | edit source]

De novo synthesis of nucleotides involves the formation of nucleotide bases from small molecules and their subsequent attachment to a sugar phosphate backbone. This process is distinct for purines and pyrimidines, the two categories of nucleotide bases.

Purine Synthesis[edit | edit source]

Purine synthesis begins with the precursor ribonucleotide, 5-phosphoribosyl-1-pyrophosphate (PRPP), and through a series of steps, adds atoms from amino acids, formate, and carbon dioxide to form the purine ring. The end products of this pathway are the purine nucleotides adenosine monophosphate (AMP) and guanosine monophosphate (GMP), which are essential for DNA and RNA synthesis.

Pyrimidine Synthesis[edit | edit source]

Pyrimidine synthesis, on the other hand, starts with the formation of the pyrimidine ring before it is attached to PRPP. The key initial step involves the enzyme carbamoyl phosphate synthetase II in the cytoplasm, differentiating it from the similarly named enzyme in the urea cycle. The end products are cytidine triphosphate (CTP) and uridine monophosphate (UMP), which can be further phosphorylated to form other nucleotides.

Salvage Pathways[edit | edit source]

The salvage pathways of nucleotide metabolism allow cells to recycle bases and nucleosides that are formed during the degradation of RNA and DNA. This process is crucial for conserving energy. The adenine phosphoribosyltransferase (APRT) and hypoxanthine-guanine phosphoribosyltransferase (HGPRT) enzymes play significant roles in these pathways, converting free bases into their corresponding monophosphate nucleotides by transferring them to PRPP.

Nucleotide Degradation[edit | edit source]

Nucleotide degradation leads to the breakdown of nucleotides into their constituent bases and sugars. In purines, this process results in the production of uric acid, which is excreted from the body. Pyrimidine degradation, however, produces beta-alanine, CO2, and ammonia, which are less toxic and can be easily excreted or recycled in other metabolic pathways.

Regulation of Nucleotide Metabolism[edit | edit source]

The metabolism of nucleotides is tightly regulated to ensure a balance between synthesis, degradation, and recycling. This balance is crucial for maintaining adequate supplies of nucleotides for DNA replication, RNA transcription, and other cellular processes. Key regulatory mechanisms include feedback inhibition, where the end products of nucleotide synthesis pathways inhibit the activity of pathway enzymes, and compartmentalization of pathways within the cell, which helps to control the availability of substrates and intermediates.

WikiMD
Navigation: Wellness - Encyclopedia - Health topics - Disease Index‏‎ - Drugs - World Directory - Gray's Anatomy - Keto diet - Recipes

Search WikiMD

Ad.Tired of being Overweight? Try W8MD's physician weight loss program.
Semaglutide (Ozempic / Wegovy and Tirzepatide (Mounjaro / Zepbound) available.
Advertise on WikiMD

WikiMD's Wellness Encyclopedia

Let Food Be Thy Medicine
Medicine Thy Food - Hippocrates

Medical Disclaimer: WikiMD is not a substitute for professional medical advice. The information on WikiMD is provided as an information resource only, may be incorrect, outdated or misleading, and is not to be used or relied on for any diagnostic or treatment purposes. Please consult your health care provider before making any healthcare decisions or for guidance about a specific medical condition. WikiMD expressly disclaims responsibility, and shall have no liability, for any damages, loss, injury, or liability whatsoever suffered as a result of your reliance on the information contained in this site. By visiting this site you agree to the foregoing terms and conditions, which may from time to time be changed or supplemented by WikiMD. If you do not agree to the foregoing terms and conditions, you should not enter or use this site. See full disclaimer.
Credits:Most images are courtesy of Wikimedia commons, and templates Wikipedia, licensed under CC BY SA or similar.

Contributors: Prab R. Tumpati, MD