title: Formation and characteristics of an unusual lambda-DNA species.
abstract: An unusual DNA species, termed as DNA species A, has been isolated and purified from thermal-denatured lambda-DNA Hind III by Sephadex G-200 gel filtration. Our studies indicate that DNA species A is resistant to DNase I digestion and has a higher melting point. The new DNA species showed a lower absorbency at 260 nm, and a lower fluorescence quantum yield after interaction with ethidium bromide (EB) than native double-stranded lambda-DNA. CD spectrum of DNA species A consists of a broad positive band centered at 245 nm and a weak negative band at 220 nm. transmission electron microscope (TEM) visualizations showed that their lengths of DNA species A fell mainly in three regions (300-500 nm, 750-1000 nm and 1500 nm) that corresponded to three fluorescence bands in the EB-stained gels. Their apparent width and height were 65-75 nm and 2.2 nm respectively as observed by images of atomic force microscope (AFM).
authors.affiliation: Insitute of Biophysics, Academia Sinica, Beijing, China.
authors.forename: E H
authors.initials: EH
authors.lastname: Cao
authors.forename: X G
authors.initials: XG
authors.lastname: Sun
authors.forename: C L
authors.initials: CL
authors.lastname: Bai
authors.forename: C Q
authors.initials: CQ
authors.lastname: Liu
authors.forename: Y J
authors.initials: YJ
authors.lastname: He
authors.forename: X W
authors.initials: XW
authors.lastname: Wang
authors.forename: Y
authors.initials: Y
authors.lastname: Fang
mesh_terms: D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry* / Q000302:isolation & purification / Q000648:ultrastructure; D018625:Microscopy, Atomic Force; D008854:Microscopy, Electron; D009690:Nucleic Acid Conformation; D013050:Spectrometry, Fluorescence
chemical_list: D004247:DNA