The isolation and identification of a novel intermediate in ubiquinone-6 biosynthesis by Saccharomyces cerevisiae.

The reaction product obtained from HeLa cell nuclei incubated with [³H]NAD was specifically hydrolyzed with snake venom phosphodiesterase. Analysis of the hydrolyzed product revealed that it is a homopolymer consisting of 4–5 repetition of ADP-ribose units. The [³H]poly ADP-ribosylated histone fraction was anslyzed by urea-acetic acid polyacrylamide gel electrophoresis. The radioactive peak was clearly separated from the stained histone H1 band, while a slight overlap was observed. When chromatographed on a SP-Sephadex C-50 column, more than 90% of the radioactivity of [³H]poly(ADP-ribose) was eluted in accordance with histones but not with nonhistone contaminants. On a sodium dodecyl sulfate polyacrylamide gel electrophoresis, a major radioactive peak appeared at a position very close to the histone Hl band, which disappeared by the treatment with alkali prior to electrophoresis. A selective extraction of histone Hl with 5% perchloric acid showed that histone Hl contained about 85% of the radioactivity incorporated into whole histones.