title: Aspects of the secondary and tertiary structure of DNA.
abstract: DNA is the primary genetic material of most organisms. A wide variety of naturally occurring duplex DNA's are known to exist as covalently closed circles. This covalent continuity introduces a topological constraint, and consequently these molecules possess aspects of tertiary and even higher-order structure. Virtually every physical, chemical and biological property of DNA - its transcription, hydrodynamic behaviour, energetics, enzymology and so on - are related to these structural features. We describe the parameters describing the topology and conformation of covalently-closed, duplex DNA's (form I DNA's), the conservation relationship between them and its implications.
mesh_terms: D000818:Animals; D010582:Bacteriophage lambda; D001482:Base Composition; D001483:Base Sequence; D002273:Carcinogens / Q000378:metabolism; D002942:Circular Dichroism; D004247:DNA / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004278:DNA, Superhelical; D004279:DNA, Viral; D004996:Ethidium; D005057:Eukaryotic Cells; D006801:Humans; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D009690:Nucleic Acid Conformation; D010957:Plasmids; D013329:Structure-Activity Relationship
chemical_list: D002273:Carcinogens; D004278:DNA, Superhelical; D004279:DNA, Viral; D046911:Macromolecular Substances; D004247:DNA; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II; D004996:Ethidium