Tamara I. Kulak

Electrodeposition of nanostructured diamond-like films by oxidation of lithium acetylide

Diamond-like carbon (DLC) films have been deposited by anodic oxidation of 4 M solution of lithium acetylide in dimethylsulfoxide on the surface of stainless steel or nickel electrode at room temperature and moderate anodic current densities (0.2–2.0 mA/cm2) in the range of electrode potentials 0.3–2.5 V (vs. sat. Ag|AgCl reference electrode). Electrodeposited DLC coatings represented complete and optically transparent films of a thickness 50–100 nm having dark island inclusions with a diameter 0.8–5.0 μm. The concentration and average size of these particles increased with the prolongation of deposition time. Micro-Raman spectra obtained by the focusing of laser beam onto these dark inclusions are characterized by a broad peak centered at 1500 cm−1 and weak peak at 1200 cm−1. With a defocused laser beam, there appear two well-distinguished peaks on the integrated Raman spectra – at 1530 and 1130 cm−1. Analysis of Raman spectra with the use of a Breit–Wigner–Fano lineshape and spectrum deconvolution indicates that the electrodeposited films consist of diamond-like nanostructured carbon with a high content (70–80%) of sp3 phase.

Synthesis of a modified 2′, 5′-Adenylate trimer with a 2′,3′-Di-O-(2-Carboxyethyl)-ethylidene terminal group

Abstract The trimer of 2′, 5′-oligoadenylic acid with a (2-carboxyethyl)ethylidene group ({=1}{=6}) at the 2′-terminal adenosine moiety and its 3′-deoxyadenosine analog ({=1}{=7}) have been synthesized by the phosphotriester method.

Pyrophosphoryl Derivatives of 1-(2-Deoxy-3-O-Phosphonomethyl-β-and-α-D-Erythro-Pentofuranosyl)Thymine: Synthesis and Substrate Properties Towards Some DNA Polymerases

Abstract The synthesis of 1-(2-deoxy-3-O-phosphonomethyl-β-D-erythro-pentofuranosyl)thymine (17) and its α-anomer 18 is described. Attempts to prepare 1-[2-deoxy-3-O-(pyrophosphoryl)phosphonomethyl-β-D-erythro- Pentofuranosyl]thymine (19) by an activation of the respective phosphonate 17 with 1,1′-carbonyldiimidazole (Im2CO) resulted in the quantitative formation of the corresponding pyrophosphonate derivative 21 (Scheme 2). Activation of inorganic pyrophosphate with Im2CO followed by the condensation with the phosphonates 17 and 18 afforded the desired analogues of nucleoside triphosphate 19 (35%) and its α-anomer 20 (27%) along with the respective pyrophosphonate derivatives 21 (37%) and 24 (38%) (Scheme 3). It was found that compounds 19 and 20 display (i) no substrate properties toward calf thymus terminal deoxynucleotidyl transferase (TDT) and AMV reverse transcriptase, and (ii) moderate substrate activity with E. coli DNA polymerase I (Klenow fragment).

Dimeric Oligonucleotide Synthons Containing 2-Deoxy-3-O-Phosphonomethyl-α-D-erythro-pentofuranosyl Nucleosides

Abstract The synthesis of 2′-deoxy-3′-O-phosphonomethyl-α-D-erythro-pentofuranosyl-thymine and -adenine (1, B is Thy or Ade) is described. Dimeric oligonucleotide synthons such as 2 containing isosteric phosphonate internucleoside linkage were prepared.

Synthesis and Biological Activity of New 2′ 5′-Oligonucleotides

Abstract Some new 2′,5′-oligonucleotide trimers containing the antiviral nucleoside ribavirin and the cytokine 6-benzylaminopurine riboside in different position of the oligos have been synthesized. Some of the trimers showed biological inhibitions of HIV-1 reverse transcriptase, HIV-1 induced syncytia formation and activation of RNase L.

Synthesis of a new 125I-labeled tyrosine methyl ester conjugate of adenylyl-(2′-5′)-adenylyl-(2′-5′)-[2′,3′-di-O-(2-carboxyethyl)ethylidene]adenosine

A novel 125I-labeled conjugate of 2′,5′-oligoadenylate trimer for radioimmuno assay of 2′,5′-oligoadenylates have been obtained by the reaction of adenylyl-(2′-5′)-adenylyl-(2′-5′)-[2′,3′-di-O-(2-carboxyethyl)ethylidene]adenosine (1) with tyrosine methyl ester followed by iodination of intermediate 2 with 125I in the presence of chloramine-T. 125I-labeled conjugate 3 was isolated by column chromatography on a TSK-gel HW-40 in 73% yield. Specific activity for the synthesized conjugate was approximately 1760 Ci/mmol.

Synthesis and Biological Activity of New Sugar Modified 2′,5′-Oligoadenylate Trimers

Abstract New 2′,5′-oligonucleotide trimers containing 2′,3′-dideoxy-3′-fluoro derivatives of adenosine at the 2′-terminal end of oligomers have been synthesized. Some of the synthesized trimers showed biological inhibitions of HIV-1 reverse transcriptase and HIV-1 induced syncytia formation.