Nucleoside


Also found in: Dictionary, Thesaurus, Medical, Wikipedia.

nucleoside

[′nü·klē·ə‚sīd]
(biochemistry)
The glycoside resulting from removal of the phosphate group from a nucleotide; consists of a pentose sugar linked to a purine or pyrimidine base.

Nucleoside

 

a compound that consists of a nitrogenous base and a carbohydrate. A nucleoside whose carbohydrate portion is ribose is called a ribonucleoside, and a deoxyribose-containing nucleoside is called a deoxyribonucleoside. Nucleosides have the following structural formula:

In deoxyribonucleosides, X is replaced by a hydrogen atom, while in ribonucleosides, a hydroxyl group replaces X. R can be any purine or pyrimidine base.

A nucleoside can be regarded as the product of the dephos-phorylation of a nucleotide. In a nucleoside, the purine or pyrimidine base is connected to the 1′ carbon atom by a β-glycoside bond. Nucleosides are named according to their base; thus, adenosine contains adenine, guanosine—guanine, uridine—uracil, cytidine—cytosine, and thymidine—thymine. The nucleosides that contain hypoxanthine and xanthine are called inosine and xanthosine, respectively. A few other nucleosides exist, which are structurally similar to those mentioned but which differ in the particular base, carbohydrate component, or type of internal bonds.

Free nucleosides are present in small quantities in several biological substances. The significance of most nucleosides, however, is their occurrence as constituents of nucleotides and nucleic acids.

I. B. ZBARSKH

References in periodicals archive ?
4) supplemented with the indicated concentration of BNO-1055, sub-fraction thereof, nucleoside transporter inhibitor or vehicle equivalent.
The team determined the chemical and physical principles a transporter molecule uses to recognize the nucleosides, "so if you can improve the interactions between the transporter and the drug, you won't need as much of the drug to get it into the tumor cells efficiently," Lee said.
6) In November 2008 the US government-sponsored antiretroviral treatment panel moved Ziagen plus Epivir off the "preferred" list of nucleoside combinations to the "alternative" list.
Participants were randomized equally to one of three arms: lopinavir soft gel capsules plus two nucleosides, efavirenz plus two nucleosides, and lopinavir soft gel capsules plus efavirenz.
HIV Patients Without Virologic Failure at 96 Weeks Efavirenz 2 + nucleosides 76% Lopinavir + efavirenz 74% Lopinavir + 2 nucleosides 67% Note: Base on a study of 753 patients.
The company leverages its expertise in nucleoside chemistry to develop therapeutics to combat infections caused by drug-resistant human immunodeficiency virus (HIV) and hepatitis viruses.
Approved March 1, 1996 for use alone or in combination with nucleoside analogues for the treatment of HIV infection.
Drugs which inhibit this step (such as nucleoside analogue reverse transcriptase inhibitors) can interrupt the process of reverse transcription.
A new kind of medication now in clinical trials blocks reverse transcriptase by attaching not at its nucleoside binding site, but in a different spot.
Under the terms of this contract, Pharmaron will continue to provide Isis with certain nucleoside phosphoramidites during the next two years.
Adenosine triphosphate (ATP), the first nucleoside triphosphate, was discovered in 1929 and synthesized in 1948.
The investigators studied changes in limb fat as measured by dual energy x-ray absorptiometry (DXA) and visceral fat as measured by computed tomography in 105 HIV-infected adults in whom zidovudine (AZT, Retrovir) or stavudine (d4T, Zerit) therapy was replaced with either the nucleoside analogue abacavir (Ziagen) or the NRTI tenofovir (Viread).

Full browser ?