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Gamma-phosphate-substituted 2'-deoxynucleoside 5'-triphosphates as substrates for DNA polymerases
A A Arzumanov1, D G Semizarov, L S Victorova
1Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov Street, Moscow 117984, Russia.
The Journal of Biological Chemistry
|October 4, 1996
Summary
Researchers synthesized novel nucleoside triphosphate analogs with modified gamma-phosphate groups. These compounds show selective substrate activity for retroviral reverse transcriptases over mammalian DNA polymerases, offering potential for targeted antiviral therapies.
Area of Science:
- Biochemistry
- Molecular Biology
- Medicinal Chemistry
Background:
- Nucleoside triphosphate analogs are crucial in antiviral drug development.
- Modifications to the triphosphate moiety can alter enzyme substrate specificity.
- 3'-azido-2',3'-dideoxythymidine 5'-triphosphate (AZTTP) is a key anti-HIV drug.
Purpose of the Study:
- To synthesize and evaluate novel 2'-deoxythymidine 5'-triphosphate and AZTTP analogs with hydrophobic phosphonate groups.
- To determine the substrate activity of these analogs against various reverse transcriptases and DNA polymerases.
- To assess the impact of gamma-phosphate modification on enzyme selectivity and metabolic stability.
Main Methods:
- Chemical synthesis of modified nucleoside triphosphate analogs.
- Enzymatic assays using human immunodeficiency virus (HIV) and avian myeloblastosis virus reverse transcriptases.
- Assays with human placental DNA polymerases alpha and beta, and calf thymus terminal deoxynucleotidyl transferase.
- Determination of Michaelis-Menten constants (Km) for substrate incorporation.
- Assessment of dephosphorylation rates in human serum and hydrophobicity.
Main Results:
- Retroviral reverse transcriptases efficiently incorporated the phosphonate analogs, while mammalian DNA polymerases did not.
- Gamma-ester and gamma-amide derivatives were substrates for both retroviral and mammalian enzymes.
- Modified AZTTP analogs showed increased selectivity for HIV reverse transcriptase inhibition over DNA polymerase alpha.
- Phosphonate analogs exhibited reduced dephosphorylation in human serum and increased hydrophobicity compared to AZTTP.
Conclusions:
- HIV and avian myeloblastosis virus reverse transcriptases accommodate bulky substituents at the gamma-position.
- Replacing the gamma-phosphate with a gamma-phosphonate group alters substrate properties for cellular DNA polymerases and dephosphorylating enzymes.
- These modifications maintain substrate activity for HIV reverse transcriptase, suggesting potential for improved antiviral agents with enhanced selectivity and stability.