NUCLEIC ACID Structure and Functions

Biomedical importance

Monomeric units or building blocks of nucleic acids.

They form a part of many coenzymes.

Donors of phosphoryl gropups (eg. ATP or GTP), of sugars (UDP- or GDP-sugars or of lipid (CDP-acylglycerol)

Serve as second messengers (eg. cAMP and cGMP )

Synthetic nucleotides

Synthetic purine and pyrimadine analogs containing halogens, thiols or additional nitrogen are used for :

chemotherapy of cancer and AIDS

Immunosuppressant for organ transplantation.

Purine and Pyrimidine

Purines and pyrimidines are nitrogen-containing heterocycles, cyclic compounds whose rings contain both carbon and other elements (hetero atoms).

Sources of the individual atoms in the purine ring.

Under physiologic conditions, the amino and oxo tautomers of purines,pyrimidine, and their derivatives predominate.

Nucleosides

Nucleosides are derivatives of purines and pyrimidines that have a sugar linked to a ring nitrogen.

The sugar is linked to the heterocyclic base via a β-N-glycosidic bond, almost always to N-1 of a pyrimidine or to N-9 of a purine.

Nucleotides

RNA RNADNA DNA

Mononucleotides are nucleosides with a phosphoryl group esterfied to a hydrosyl group of the sugar. 3’- and 5’ –nucleotides are nucleosides with a phosphoryl group on the 3’ – or 5’ –hydroxyl group of the Sugar.

Nucleotides

Nucleostides are present in all type of cells.

Ribonucleoside monophosphate, diphosphate, and triphosphate.

Conversion of nucleoside monophosphates to nucleoside diphosphates and triphosphates.

Conversion of ribonucleotides to deoxyribonucleotides.

Cyclic AMP and GMP

Adenylate cyclase

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Dinucleotide

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