• Home
  • Search Results
  • Osmium tetroxide: a new probe for site-specific distortions in supercoiled DNAs.

Osmium tetroxide: a new probe for site-specific distortions in supercoiled DNAs.

Nucleic acids research (1984-02-10)
G C Glikin, M Vojtískova, L Rena-Descalzi, E Palecek
ABSTRACT

Supercoiled plasmids Col E1 and cDm 506 (a Col E1 derivative carrying the D. melanogaster histone gene repeat) were treated with OsO4 in presence of pyridine and the reaction products were analyzed using different approaches. Gel electrophoresis showed that OsO4 binding to supercoiled DNA induced its relaxation without nicking. The amount of osmium bound to DNA (as determined electrochemically) increased with the extent of DNA relaxation. As a result of osmium modification of supercoiled cDm 506, a single denaturation "bubble" was observed in the electron microscope. Mapping of the osmium binding site by S1 nuclease cleavage followed by restriction enzyme digestion has revealed one major site in the intergenic spacer between the H1 and H3 histone genes of D. melanogaster. This site differs from the site cleaved by S1 nuclease in supercoiled DNA in the absence of osmium.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Osmium tetroxide solution, suitable for electron microscopy, 4% in H2O