Nucleoside


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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 ?
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.
Recently, INFORM-1, a short term phase-1 study has shown that Danoprevir in combination with a nucleoside polymerase inhibitor (RG 7128), both used orally are able to suppress HCV replication without RBV or INF.
To determine the absolute risk of MI among nucleoside analogue users, the investigators incorporated the Framingham predicted 10-year coronary heart disease risk into the main regression model, and determined that the rate of MI was increased by 119% in patients with a moderate 10-year risk and by 222% in patients with a high 10-year risk, relative to those with a low 10-year risk, Dr.
The two main biochemical mechanisms leading to NRTI (nucleoside analogue reverse transcriptase inhibitor) resistance are:
Kohler and two of his graduate students took portions of the DNA molecule called nucleosides, placed them in water, and then bombarded them with an ultrashort pulse of UV light from a laser.
Approved June 24, 1996 for use in combination with nucleoside analogues for the treatment of HIV-infected adults experiencing clinical and/or immunologic deterioration.
Until recently the only approved form of therapy for HIV infection was treatment with drugs from the class of nucleoside analogue reverse transcriptase inhibitors (see Table 1), often referred to as RT inhibitors or nucleoside analogues.
AstraZeneca, a UK-based pharmaceutical company, and MedImmune, its global biologics research and development arm, announced on Friday that the US Food and Drug Administration (FDA) has approved Lumoxiti (moxetumomab pasudotox-tdfk) for the treatment of adult patients with relapsed or refractory hairy cell leukaemia (HCL) who have received at least two prior systemic therapies, including treatment with a purine nucleoside analog.
According to the company, Lumoxiti (moxetumomab pasudotox-tdfk) injection for intravenous use has been approved for the treatment of adult patients with relapsed or refractory hairy cell leukemia (HCL) who have received at least two prior systemic therapies, including treatment with a purine nucleoside analog.
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Initial treatment regimens for chronic HBV consist of monotherapy with interferon-[alpha], pegylated interferon-[alpha], or nucleoside analogues.
The regimens for first-line therapy of HIV that are currently recommended by the Department of Health and Human' Services are the protease inhibitor lopinavir and the nonnudeoside reverse transcriptase inhibitor efavirenz, each given with two nucleoside reverse transcriptase inhibitors.

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