This work was supported by United States Public Health Service Grants 1-RO1-CA-23296, CA-28704 and 1-26-CA-14134.
Article first published online: 8 MAR 2005
Copyright © 1981 Wiley-Liss, Inc.
Volume 2, Issue 4, pages 201–211, January 1982
How to Cite
Kapuscinski, J., Darzynkiewicz, Z. and Melamed, M. R. (1982), Luminescence of the solid complexes of acridine orange with RNA. Cytometry, 2: 201–211. doi: 10.1002/cyto.990020402
Presented at VIII Conference on Analytical Cytology and Cytometry, Wentworth-by-the-Sea, New Hampshire, May 19–25, 1981. Abstract: Cytometry 2: 107, 1981
- Issue published online: 16 JUN 2005
- Article first published online: 8 MAR 2005
- Manuscript Accepted: 2 JUL 1981
- Manuscript Received: 18 FEB 1981
- RNA, acridine orange;
- cooperative transition;
- flow cytometry
The products of interaction between acridine orange (AO) and natural RNA, or the synthetic RNA homopolymers are precipitates insoluble over a wide range of ionic strength. These complexes have a composition of 1 AO molecule per 1 phosphatate. The reaction is highly cooperative and the complex exhibits metachromatic luminescence. Significant differences in the luminescence spectra, related to base composition of RNA, characterize the insoluble complexes. This observation suggests that dye-base interactions take place in the AO-RNA complexes.
During titration of poly(rA) with AO and simultaneous measurement of the luminescence and light scatter a two-step formation of the particles could be detected. The cooperative binding of the ligand at D/P < 0.6 coincides with formation of small particles (molecular aggregates or micelles) and is followed at D/P > 0.6 by a cooperative agglomeration; the product of this agglomeration is particles of the size 0.35 μm and larger.
Evidence is presented that suggests that the long wavelength luminescence (∼ 650 nm) is a consequence of the solute-solid state transition of the AO-RNA interaction product rather than the classic dye-dye interactions previously visualized in the stacking model. Since these novel observations cannot be fully explained by the previously postulated molecular mechanisms of AO binding, an alternative model is advanced. Its implications in quantitative cytochemistry of nucleic acid as applied to flow cytometry are discussed.