Deoksiriboosin

Deoksiriboosin, commonly referred to as deoxyribose, is a five-carbon sugar that forms a key component of deoxyribonucleic acid (DNA). As the sugar moiety in deoxynucleotides, it links to nitrogenous bases to form deoxynucleosides and, after phosphorylation, deoxynucleotide triphosphates that serve as substrates for DNA synthesis.

Chemical and structural properties

Deoxyribose is a reduced form of ribose, lacking an oxygen atom at the 2' position (2'-deoxyribose). In DNA, the sugar predominantly adopts the beta-D-2-deoxyribofuranose form, a five-membered ring that connects to phosphate groups at the 3' and 5' positions to form the sugar-phosphate backbone. Its chemical formula is C5H10O4.

Biological context

In cells, deoxyribose is produced as part of nucleotide biosynthesis. Ribonucleotide reductase converts ribonucleotides to their deoxy counterparts, producing deoxynucleoside monophosphates that are further phosphorylated to deoxynucleotide triphosphates. DNA polymerases use these substrates to synthesize DNA, extending chains at the 3' end.

Functional significance

The absence of the 2' hydroxyl group in deoxyribose makes DNA chemically more stable than RNA, contributing to its role in long-term genetic storage. The sugar's stereochemistry and conformation help define the overall geometry of the DNA sugar-phosphate backbone, influencing DNA structure and replication.

Etymology

The name derives from the prefix "deoxy-" (without oxygen) and "ribose," the five-carbon sugar in nucleic acids.