Fluormetric studies on the ribosomal structure by ethidium bromide
Yamada, M.O.; Kinouchi, Y.; Fujimori, K.; Yamamoto, K.
Cellular and Molecular Biology Including Cyto-Enzymology 23(2): 183-190
1978
ISSN/ISBN: 0145-5680 PMID: 719669 Document Number: 135943
The complex of ethidium bromide (EB) with ribosomes was studied on the rat liver cells and liver ribosomal fractions. The fluorescence was characterized in relating to the ribosomal structure. The fluorescence emitted at 590 nm (RF590) was changed by the treatment with EDTA which caused dissociation of the ribosomal subunits. The subunits bound to EB were fractionated in a 15-30% sucrose gradient centrifugation in 10 mM Tris-HCl and 10 mM KCl. A similar fluorescent nature was observed in the EB complexes between both the subunits. There were 2 excitation maxima at 300 nm (Ex300) and 330 nm (Ex330). The RF590 at Ex330 was decreased to 10% of the original RF by addition of 5 mM Mg2+. The highest decrease was resulted in the RF at 595 nm observed in Ex330. Dissociated subunits may have many sites of RNA for binding to EB, which results in a marked increase of the fluorescence. The exposed RNA sites may disappear with the association of subunits by adding Mg2+. The fluorometry seems useful to show the profile of the ribosomal structure in combination with Mg2+.