Viewing of Complex Molecules of Ethidium Bromide and Plasmid DNA in Solution by Atomic Force Microscopy

• Published in: Chemical & pharmaceutical bulletin Vol. 49; no. 4; pp. 413 - 417
• Main Authors: UTSUNO, Kuniharu, TSUBOI, Masamichi, KATSUMATA, Shunji, IWAMOTO, Toschitake
• Format: Journal Article
• Language: English
• Published: Tokyo The Pharmaceutical Society of Japan 2001; Maruzen; Japan Science and Technology Agency
• Subjects: atomic force microscopy; Biological and medical sciences; DNA - chemistry; DNA - ultrastructure; Electrophoresis, Polyacrylamide Gel; Ethidium - chemistry; ethidium bromide; Fundamental and applied biological sciences. Psychology; Intermolecular phenomena; interwound form of DNA duplex; Microscopy, Atomic Force; Miscellaneous; Molecular biophysics; Nucleic Acid Conformation; plasmid DNA; Plasmids - chemistry; Plasmids - ultrastructure; plectonemic form of DNA duplex; Solutions; Spectrophotometry, Infrared; Plasmid; Atomic force microscopy; Molecular structure; Medium effect; Superhelical structure; Tertiary structure; DNA; Molecular intercalation; Concentration effect; Molecular dynamics; Molecular interaction; Aqueous solution
• ISSN: 0009-2363; 1347-5223
• DOI: 10.1248/cpb.49.413

Tertiary structure changes in plasmid DNA, induced by ethidium bromide intercalation, have been observed in aqueous solutions by the use of an atomic force microscoe. A relaxed closed circular pBR322 molecule became a positively supercoiled complex on the drug binding. The supercoiling always resulted in an interwound (or a plectonemic) form, but never a solenoidal (or a toroidal) form. A quantitative analysis of the compactness of such supercoiled complexes has been carried out.