title: DNA interaction with Mn2+ ions at elevated temperatures: VCD evidence of DNA aggregation.
abstract: Interaction of natural calf thymus DNA with Mn(2+) ions was studied at room temperature and at elevated temperatures in the range from 23 degrees C to 94 degrees C by means of IR absorption and vibrational circular dichroism (VCD) spectroscopy. The Mn(2+) concentration was varied between 0 and 1.3M (0 and 10 [Mn]/[P]). The secondary structure of DNA remained in the frame of the B-form family in the whole ion concentration range at room temperature. No significant DNA denaturation was revealed at room temperature even at the highest concentration of metal ions studied. However at elevated temperatures, DNA denaturation and a significant decrease of the melting temperature of DNA connected with a decrease of the stability of DNA induced by Mn(2+) ions occurred. VCD demonstrated sensitivity to DNA condensation and aggregation as well as an ability to distinguish between these two processes. No condensation or aggregation of DNA was observed at room temperature at any of the metal ion concentrations studied. DNA condensation was revealed in a very narrow range of experimental conditions at around 2.4 [Mn]/[P] and about 55 degrees C. DNA aggregation was observed in the presence of Mn(2+) ions at elevated temperatures during or after denaturation. VCD spectroscopy turned out to be useful for studying DNA condensation and aggregation due to its ability to distinguish between these two processes, and for providing information about DNA secondary structure in a condensed or aggregated state.
authors.affiliation: Department of Chemistry, Faculty of Science, University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4, Canada.
authors.forename: Valery
authors.initials: V
authors.lastname: Andrushchenko
authors.forename: Hans
authors.initials: H
authors.lastname: Van De Sande
authors.forename: Hal
authors.initials: H
authors.lastname: Wieser
mesh_terms: D000818:Animals; D002942:Circular Dichroism / Q000295:instrumentation / Q000379:methods*; D004247:DNA / Q000737:chemistry*; D019281:Dimerization; D008345:Manganese / Q000737:chemistry*; D013055:Spectrophotometry, Infrared / Q000295:instrumentation / Q000379:methods*; D013696:Temperature
chemical_list: D008345:Manganese; D004247:DNA; C427203:calf thymus DNA