Abstract
Transmission electron microscopy and scanning force microscopy of negative-stained, carbon-coated replica and mica-adsorbed preparations of 200 μM poly r(A-U) and 50 μM ethidium bromide/200 μM poly r(A-U) have been employed to evaluate ethidium-induced changes in poly r(A-U) topology. Poly r(A-U) alone exhibits elongated conformations 85-115 nm in length that possess a number of hairpin loops as well as single-stranded domains. While the double-stranded domains are found predominately at the base of the hairpin loops (diameter = 5-30 nm), other rod-like (presumably double-stranded) regions ranging from 25-80 nm in length are present in other portions of the poly r(A-U). In contrast with the poly r(A-U) alone, the EB/poly r(A-U) combination appears as a heterogeneous population of condensed structures whose lengths and widths vary from 12-88 nm and 15-45 nm, respectively. These conformational changes are due to a number of factors, including the displacement of ordered water surrounding the poly r(A-U) and charge shielding of the phosphate groups of the poly r(A-U) upon the binding of the ethidium.
Original language | English (US) |
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Pages (from-to) | 523-532 |
Number of pages | 10 |
Journal | Scanning |
Volume | 19 |
Issue number | 8 |
DOIs | |
State | Published - Nov 1997 |
Keywords
- Atomic force microscopy
- Double-stranded RNA
- Electron microscopy
- Ethidium bromide
- Polyribonucleotides
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Instrumentation