Linear Dichroism Characteristics of Ethidium and Proflavine Supercoiled DNA Complexes
Abstract
A flow linear dichroism technique is utilized to study the unwinding of supercoiled DNA induced by the binding of ethidium bromide (EB) and proflavine (PF) at different ratios r (drug added/DNA base). In the case of either EB or PF bound to linear calf thymus DNA, the reduced linear dichroism signals LD/A (LD: linear dichroism; A: absorbance, both measured at the same wavelength), determined at 258, and 520 or 462 nm (corresponding to contributions predominantly from the partially oriented DNA bases, intercalated EB, or PF, respectively) are nearly independent or drug concentration. In the case of supercoiled DNA, the magnitude of LD/A at 258 nm first increases to a maximum value near r = 0.04-0.05, and then decreases as r is increased further, mimicking the behavior of the sedimentation coefficients, viscosities, and gel electrophoresis patterns measured by other workers at similar values of r. Reprints.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1990
- Accession Number
- ADA227780
Entities
People
- Charles E. Swenberg
- Nicholas E. Geacintov
- Susan E. Carberry
Organizations
- Armed Forces Radiobiology Research Institute