Phosphodiester bond


Phosphodiester bond

A phosphodiester bond is a group of strong covalent bonds between the phosphorus atom in a phosphate group and two other molecules over two ester bonds. Phosphodiester bonds are central to all life on Earth, as they make up the backbone of the strands of DNA. In DNA and RNA, the phosphodiester bond is the linkage between the 3' carbon atom and the 5' carbon of the sugar deoxyribose (in DNA) or ribose (in RNA).

The phosphate groups in the phosphodiester bond are negatively-charged. Because the phosphate groups have a pKa near 0, they are negatively-charged at pH 7. This repulsion forces the phosphates to take opposite sides of the DNA strands and is neutralized by proteins (histones), metal ions such as magnesium, and polyamines.

In order for the phosphodiester bond to be formed and the nucleotides to be joined, the tri-phosphate or di-phosphate forms of the nucleotide building blocks are broken apart to give off energy required to drive the enzyme-catalyzed reaction. When a single phosphate or two phosphates known as pyrophosphates break away and catalyze the reaction, the phosphodiester bond is formed.

Hydrolysis of phosphodiester bonds can be catalyzed by the action of phosphodiesterases which play an important role in repairing DNA sequences.

In biological systems, the phosphodiester bond between two ribonucleotides can be broken by alkaline hydrolysis because of the free 2' hydroxyl group.

Enzyme activity

A phosphodiesterase is an enzyme that catalyzes the hydrolysis of phosphodiester bonds, for instance a bond in a molecule of cyclic AMP or cyclic GMP.

An enzyme that plays an important role in the repair of oxidative DNA damage is the 3'-phosphodiesterase.

During the replication of DNA, there is a hole between the phosphates in the backbone left by DNA polymerase I. DNA ligase is able to form a phosphodiester bond between the nucleotides.

See also

*Phosphodiesterase
*Phosphodiesterase inhibitor
*DNA replication, DNA, ATP
*Teichoic acid, DNase I
*PDE5


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Look at other dictionaries:

  • phosphodiester bond — n a covalent bond in RNA or DNA that holds a polynucleotide chain together by joining a phosphate group at position 5 in the pentose sugar of one nucleotide to the hydroxyl group at position 3 in the pentose sugar of the next nucleotide called… …   Medical dictionary

  • phosphodiester bond — phospho diester bond A bond in which a phosphate group joins adjacent carbons through ester linkages. A condensation reaction between adjacent nucleotides results in a phosphodiester bond between 3 and 5 carbons in DNA and RNA …   Glossary of Biotechnology

  • phosphodiester bond — fosfodiesterinis ryšys statusas T sritis chemija apibrėžtis Nukleorūgščių pagrindinis ryšys, susidarantis per fosfato rūgštį tarp dviejų ribozių 3′ ir 5′ hidroksigrupių. formulė (–O)₂P(=O)OH atitikmenys: angl. phosphodiester bond rus.… …   Chemijos terminų aiškinamasis žodynas

  • phosphodiester bond — ¦fäs(ˌ)fōˌ… noun or phosphodiester linkage : a covalent bond in RNA or DNA that holds a polynucleotide chain together by joining a phosphate group at position 5 in the pentose sugar of one nucleotide to the hydroxyl group at position 3 in the… …   Useful english dictionary

  • phosphodiester bond — Not a precise term. Refers to any molecule in which two parts are joined through a phosphate group. Examples are found in RNA, DNA, phospholipids, cyclic nucleotides, nucleotide diphosphates and triphosphates …   Dictionary of molecular biology

  • phosphodiester — A diesterified orthophosphoric acid, RO–(PO2H)–OR′, as in the nucleic acid s. p. hydrolases SYN: phosphodiesterases. * * * phos·pho·di·es·ter dī es tər n an oligonucleotide with an oxygen atom linking consecutive nucleotides see …   Medical dictionary

  • phosphodiester linkage — noun see phosphodiester bond …   Useful english dictionary

  • phospho-diester bond — phosphodiester bond A bond in which a phosphate group joins adjacent carbons through ester linkages. A condensation reaction between adjacent nucleotides results in a phosphodiester bond between 3 and 5 carbons in DNA and RNA …   Glossary of Biotechnology

  • nucleic acid — /nooh klee ik, klay , nyooh /, Biochem. any of a group of long, linear macromolecules, either DNA or various types of RNA, that carry genetic information directing all cellular functions: composed of linked nucleotides. [1890 95; NUCLE(US) + IC;… …   Universalium

  • Hammerhead ribozyme — Taxobox | color=white name = Hammerhead Ribozyme image caption = Stylized rendering of the full length hammerhead ribozyme RNA molecule species = Catalytic RNAHammerhead RNAs are small self cleaving RNAs that have a conserved motif found in… …   Wikipedia


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