Arthur D. Broom

A novel synthesis of nucleoside 5′-triphosphates

Facile syntheses of ribonucleoside 5′-triphosphates have been accomplished in good yield (>60%) in a one-pot reaction of unprotected nucleosides with phosphoryl chloride followed by treatment of the resulting phosphorodichloridate with tri-n-butylammonium phosphate in the presence of dimethylformamide.

Synthesis o an 8-deaza analog of the intermediate in the thymidylate synthetase reaction

Abstract Synthesis of an 8-deaza analog of the proposed intermediate in the thymidylate synthetase reaction was accomplished from diethyl 8-deazafolic acid an unambiguous proof of the structure is provided.

One-step chemical synthesis of ribonucleosides bearing a photolabile ether protecting group

Ribonucleosides bearing a photolabile protecting function, the o-nitrobenzyl group, which may be cleaved without affecting either purine or pyrimidine bases, have been produced in one step from unprotected ribonucleosides.

PMTI, a broadly active unusual single-stranded polyribonucleotide, inhibits human immunodeficiency virus replication by multiple mechanisms

Poly(1-methyl-6-thioinosinic acid), or PMTI, is a single-stranded polyribonucleotide and is the first homopolyribonucleotide devoid of Watson—Crick hydrogen bonding sites to show potent human immunodeficiency virus (HIV) inhibition. PMTI was found to be active when evaluated against a variety of low passage clinical HIV isolates in fresh human peripheral blood cells, including T cell-tropic and monocyte—macrophage-tropic viruses, syncytium-inducing and non-syncytium-inducing viruses and viruses representative of the various HIV-1 clades (A through F). The compound was active against HIV-2, all nucleoside and non-nucleoside reverse transcriptase (RT) inhibitor drug-resistant virus isolates tested and interacted with AZT or ddI to synergistically inhibit HIV infection. In biochemical inhibition assays, PMTI was determined to be a potent inhibitor of HIV-1 and HIV-2 RT, including RTs with mutations that engender resistance to nucleoside and non-nucleoside RT inhibitors. PMTI inhibited both the polymerase and RNase H activities of HIV RT. PMTI did not inhibit HIV-1 protease or integrase. Cell-based mechanism of action assays indicated that PMTI also interfered with early events in the entry of HIV into target cells. Furthermore, PMTI inhibited the fusion of gp120-expressing and CD4-expressing cells, but at concentrations approximately 1 log10 greater than those that inhibited virus entry. These results suggest that the homopolyribonucleotide PMTI blocks HIV replication in human cells at its earliest stages by multiple mechanisms, inhibition of virus entry and inhibition of RT.

THE ROLE OF HYDROPHOBIC VERSUS HYDROPHILIC BASE CHARACTER IN THE ANTI-HIV ACTIVITY OF PURINE-CONTAINING POLYRIBONUCLEOTIDES

Abstract ABSTRACT In contrast to the highly amphiphilic poly(1-methyl-6-thioinosinic acid), a potent anti-HIV agent, poly(1-amino-6-thioinosinic acid) (PATI) lacks the unique melting behavior characteristic of the amphiphilic polymers and is completely devoid of anti-HIV activity. This is consistent with the hypothesis that amphiphilic character and the ability to form an ordered secondary structure in solution are prerequisites for potent anti-HIV activity of single-stranded polynucleotides.

Polyribonucleotides containing thiopurines: synthesis and properties.

Abstract The synthesis of poly(1-methyl-6-thioinosinic acid) and a comparison of its properties with those of poly(6-thioinosinic acid) and poly(6-methylthiopurinylic acid) are reported. In contrast to 6-thioinosine 5′-diphosphate, 1-methyl-6-thioinosine 5′-diphosphate was found to be a substrate for polynucleotide phosphorylase-catalyzed homopolyribonucleotide synthesis. Poly(1-methyl-6-thioinosinic acid) appears to form a single stranded helical array with a highly cooperative melting transition (Tm = 12°C) and a very large bathochromic shift (12 nm) in the absorption maximum upon melting.

Probing the Thymidylate Synthase Active site with Bisubstrate Analog Inhibitors

Abstract Earlier reports on the enhancement of folate analog binding to thymidylate synthase (TS) by N10-propargylation prompted the synthesis of a bisubstrate analog containing an 8-deaza-N10-propargyl-5,6,7,8-tetrahydrofolate moiety coupled through a methylene linkage to 2′-deoxyuridylate.

Structure and Stability of an Oligonucleotide Containing 2′-Deoxy-6-thioguanosine

Abstract Structure and stability of the self-complementary octamers d(AAACGTTT) and d(AAACs6GTTT) have been evaluated by one and two-dimensional NMR and UV techniques. Temperature dependence studies by NMR and UV indicate the presence of 2′-deoxy-6-thioguanosine (ds6G) acts to destabilize duplex formation in the octamer by about 10 to 15°C. Comparison of octamers indicate the presence of ds6G octamer acts to induce structural perturbations that are not localized to the central dC-ds6G base pairs but affect the overall structure of the entire octamer.

Polyribonucleotides. The Role of Acid/Base Properties in Hydrogen Bond Interactions

Abstract Three new polyribonucleotides, poly (3-deazauridylic acid), poly (2-fluoroinosinic acid) and “poly (ribavirinic acid)” were synthesized. These compounds were designed to explore the importance and limits of the acidic properties of putative Watson-Crick hydrogen bonding protons in forming duplexes with complementary polynucleotides. None of these polymers formed such duplexes, thus establishing that a limited range of acidities is required.

An Unusual “Senseless” 2′,5′‐Oligoribonucleotide With Potent Anti‐Hiv Activity

A new 32‐mer 2′,5′‐oligoribonucleotide of 1‐methyl‐6‐thioinosinic acid (10) has been synthesized. The design of this unique oligoribonucleotide is based on the reported HIV inhibitory activities of both 2′,5′‐oligonucleotides and the 3′,5′‐oligoribonucleotides containing the 1‐methyl‐6‐mercaptopurine base. Tm and CD studies of 10 revealed that it has no organized secondary structure, presumably due to the rigidity of the molecule. The synthesized oligomer, 10, showed a potent inhibitory effect on HIV‐1RF and significantly inhibited HIV‐1 reverse transcriptase. †In honor and celebration of the 70th birthday of Professor Leroy B. Townsend.