5e Chapter25 2003

5e Chapter25 2003 - 2002, 2003 by Changwon Kang Chapter 25:...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 25 1 Chapter 25: Nucleotide Biosynthesis A. Nucleotides and derivatives are: (1) Activated precursors of DNA and RNA (e.g. dNTP, rNTP), (2) Sources of energy and activation (e.g. ATP, GTP), and donor of phosphoryl group (e.g. ATP), (3) Activated intermediates in biosynthesis (eg. UDP-glucose, CDP-diacylglycerol), (4) Second messengers of signal transduction between and within cells (e.g. cAMP, cGMP), and (5) Components of major coenzymes (e.g. NAD + , FAD, CoA). B. De novo synthesis (1) Chemically, nucleotides are phosphate-sugar-base (nucleosides are sugar-base). Biochemically, they are derived from 5-phosphoribosyl-1-pyrophosphate (PRPP) that is an activated form of ribose 5-phosphate. committed step PRPP P ribose NH 2 IMP (Inosinate) Gln Gly THF Gln BiC Asp THF Carbamoy laspartate Orotate OMP (Orotidylate) Asp committed Gln step Bicarbonate Carbamoyl phosphate 2 ATP (2) Purine nucleotides are derived from IMP. d G M P d G D P d G T P Gln +ATP GMP GDP GTP AMP ADP ATP Asp +GTP d A M P d A D P d A T P (3) Pyrimidine nucleotides are derived from OMP through UMP. dTMP dTDP dTTP d U M P d U D P d U T P OMP UMP UDP UTP C M P C D P CTP dCMP dCDP dCTP (4) Summary Phosphate-sugar moiety is from PRPP. Base ring scaffolds are made from Gln, Asp, Gly, formyl THF, and CO 2 .
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 3

5e Chapter25 2003 - 2002, 2003 by Changwon Kang Chapter 25:...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online