title: Cationic agents for DNA compaction.
abstract: Fluorescence microscopy was used to investigate the conformational changes of individual T4 DNA molecules induced by different compacting agents, namely the cationic surfactants, cetyltrimethylammonium bromide (CTAB) and chloride (CTAC), iron(III), lysozyme, and protamine sulfate. A protocol for establishing size estimates is suggested to obtain reproducible results. Observations show that in the presence of lysozyme and protamine sulfate, DNA molecules exhibit a conformational change from an elongated coil structure to compact globules, usually interpreted as a first-order transition. The maximum degree of compaction that is attained when iron(III) or CTAB (CTAC) are used as compacting agents is considerably smaller, and intermediate structures (less elongated coils) are visible even for high concentrations of these agents. Dynamic light scattering experiments were carried out, for some of the systems, to assess the reliability of size estimates from fluorescence microscopy.
authors.affiliation: Chemistry Department, Coimbra University, 3004-535 Coimbra, Portugal.
authors.forename: Sylwia
authors.initials: S
authors.lastname: Gaweda
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Morán
authors.forename: Alberto A C C
authors.initials: AA
authors.lastname: Pais
authors.forename: Rita S
authors.initials: RS
authors.lastname: Dias
authors.forename: Karin
authors.initials: K
authors.lastname: Schillén
authors.forename: Björn
authors.initials: B
authors.lastname: Lindman
authors.forename: M Graça
authors.initials: MG
authors.lastname: Miguel
mesh_terms: D017122:Bacteriophage T4 / Q000378:metabolism; D002412:Cations; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D004279:DNA, Viral / Q000737:chemistry; D007501:Iron / Q000737:chemistry; D008027:Light; D008856:Microscopy, Fluorescence / Q000379:methods; D009113:Muramidase / Q000737:chemistry; D009690:Nucleic Acid Conformation; D011479:Protamines / Q000737:chemistry; D011487:Protein Conformation; D012542:Scattering, Radiation; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D002412:Cations; D002593:Cetrimonium Compounds; D002712:Chlorides; D004279:DNA, Viral; D011479:Protamines; D013501:Surface-Active Agents; D004247:DNA; D007501:Iron; D009113:Muramidase; D000077286:Cetrimonium