MULTINUCLEAR NMR STUDIES OF CATION-DNA INTERACTIONS

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The primary objectives of this project are to characterize multivalent cation binding environments on DNA and to explore how these environments change over the course of a biologically important DNA structural transition, the B-Z transition. Specifically, a series of 59 Co NMR measurements are proposed in order (l) to clarify the 59 Co NMR relaxation behavior of Co (NH3)63+ bound to DNA, in particular with respect to the influence of cation mobility on the surface of the DNA (2) to examine base composition, sequence and DNA length effects on Co(NH3)63+ binding strength and heterogeneity and (3) to monitor the state of Co(NH3)63+ over the B-Z transition of synthetic DNA. Additional experiments are proposed using 13C and 15N NMR measurements in order (1) to characterize the dilute-solution behavior of specifically labeled polyamines (2) to determine the local pKa's of polyamines bound to DNA (3) to characterize polyamine binding to natural, synthetic and oligomeric DNA's (4) to examine the mobility of polyamines trapped near the DNA surface and (5) to probe polyamine involvement in the B-Z transition.