Structure of Nucleoside and Nucleotide

In this structure of nucleoside and nucleotide post we have briefly explained about nucleoside in DNA, nucleotide, and nucleoside triphosphates.

Structure of Nucleoside and Nucleotide

A nucleoside in DNA is a unit that consists of a sugar molecule covalently linked to a nitrogenous base. A beta glycosidic linkage is the bond that connects these two structures.

Adenosine, guanosine, cytidine, and uridine are the four nucleosides found in RNA molecules. Deoxyadenosine, deoxyguanosine, deoxycytidine, and thymidine are the four nucleosides found in DNA molecules.

A nucleotide is defined as a nucleoside with one or more phosphate groups connected to the sugar. Adenosine 5′-triphosphate is an example of a nucleotide (ATP). This is the most prevalent biological molecule for storing energy required for cellular reactions.

There was no precipitin ring visible, which could be due to serum inactivation, unlabelled antigen filling in the wells, or agarose gel drying during incubation. Due to poor gel pouring and antiserum inactivation, a blur precipitin ring was seen.

Nucleosides

When bases are linked to the pentose sugar D-ribose or 2-deoxy D-ribose, nucleosides are produced. A beta-N-glycosidic link between the 1st carbon of the pentose sugar and N9 of a purine or N1 of a pyrimidine attaches all bases to the corresponding pentose sugar.

Nucleosides

Sugar groups in nucleic acids

The prefix d- is used before the nucleoside to indicate deoxy nucleosides. To avoid confusion with the carbon atoms of the purine or pyrimidine ring, the carbon atoms of the pentose sugar are designated by a prime number.

Nucleosides

Numbering in base and sugar groups. Atoms in sugar is denoted with primed numbers

Purine nucleosides have the suffix sine, whereas pyrimidine nucleosides have the suffix -dine. Uracil combines with ribose only; and thymine with deoxy ribose only.

Nucleotide

These are nucleoside phosphate esters. A nucleotides in DNA is made up of a base, pentose sugar, and phosphoric acid. The esterification takes place at the pentose sugar’s 5th or 3rd hydroxyl group. 5′-phosphates make up the majority of nucleoside phosphates involved in biological function.

Because 5′-nucleotides are more commonly encountered, they are written without a prefix. 5′-AMP, for example, is abbreviated as AMP, but 3′-AMP is always written as 3′-AMP.

A base can also interact with ribose or deoxy ribose, which can then be phosphorylated at the 3′ or 5′ locations. Many co-enzymes are adenosine monophosphate derivatives. NAD+, NADP, FAD, and Co-enzyme A are among examples.

The wavelength of light that nucleotides and nucleic acids absorb is 260 nm, which is used to quantify them. Chemical changes are formed when nucleic acids absorb ultraviolet radiation, resulting to mutation and cancer.

Nucleoside Triphosphates

By esterifying additional phosphate groups to the existing ones, corresponding nucleoside di- and triphosphates are produced. NTP or d-NTP is the abbreviation for any nucleoside triphosphate.

One high energy bond exists in a nucleoside diphosphate, while two high energy bonds exist in triphosphates. The universal energy currency is ATP. It is generated by trapping the released energy in the high energy phosphate bond during oxidative reactions.

Nucleosides

Adenosine triphosphate (ATP)

Between the 3′ and 5′ locations of the ribose group, a phosphodiester bond can occur. Cyclic nucleotides are a type of cyclic nucleotide. cAMP, or 3′, 5′-cyclic AMP, is a key metabolic regulator. Cyclic GMP behaves in a similar way. These are second messengers that have a role in the activity of a variety of hormones.

Nucleosides

3′,5′-cyclic AMP or cAMP

Deoxy ribonucleotides are used to make DNA, while ribonucleotides are used to make RNA. Instead of a C-N link, uridine is connected to ribose phosphate in a C-C bond in pseudouridylic acid (present in tRNA).

Nucleosides

Different attachment of uracil to sugars

Further Readings

Reference

  1. https://pubs.acs.org/doi/abs/10.1021/bc9701508
  2. https://www.tandfonline.com/toc/lncn19/18/4-5
  3. https://www.alfa.com/en/nucleosides-nucleotides/
  4. https://www.britannica.com/science/nucleic-acid