[Enzymatic synthesis of beta-NAD+ selectively marked with tritium at adenine and its use for determining the activity of poly(ADP-ribose) polymerase]. / Fermentativnyi sintez selektivnomechennogo tritiem po adeninu beta-NAD+ i ego ispol'zovanie dlia opredeleniia akativnosti poli(ADF-riboza)-polimerazy.

A method of preparation of tritiated beta-HA [symbol: see text]+ from (adenine-2,8-(3)H)ATP and nicotinamide mononucleotide is suggested. This method is based on the baker's yeast (Saccharomyces cerevisiae) enzyme nicotinamide nucleotide adenylyltransferase. Experimental conditions for a nearly complete conversion of labeled ATP to NAD were determined. The tritiated NAD prepared by this method can be used in the quantitative assay of the chromatin enzyme poly(ADP-ribose) polymerase.

[Phosphorylation of 5'-O-phosphonylmethylthymidine and its incorporation into HeLa cells DNA]. / Fosforilirovanie 5'-O-fosfonilmetiltimidina i ego vkliuchenie v DNK kletok HeLa.

[3H]5'-O-Phosphonylmethylthymidine with a specific activity of 71 Ci/mmol was obtained by isotope exchange. Its incubation with a HeLa cell culture resulted in the formation of [3H]-labeled 5'-O-(beta-phosphoryl-alpha-phosphonylmethyl)thymidine, 5'-O-(beta,gamma-diphosphoryl-alpha-phosphonylmethyl)thymidine, and [3H]DNA. This proved the ability of 5'-O-phosphonylmethylthymidine to undergo phosphorylation and incorporation into the DNA of human cells.