Long-range DNA charge transport

The stack of base pairs within double helical DNA has been shown to mediate charge transport reactions. Charge transport through DNA can result in chemistry at a distance, yielding oxidative DNA damage at a site remote from the bound oxidant. Since DNA charge transport chemistry depends on coupling within the stacked base pair array, this chemistry is remarkably sensitive to sequence-dependent DNA structure and dynamics. Here, we discuss different features of DNA charge transport chemistry, including applications as well as possible biological consequences and opportunities.     

Substrate specificity of NovM: implications for novobiocin biosynthesis and glycorandomization

[reaction: see text] In an effort to expand the scope of natural product in vitro glycorandomization (IVG), the substrate specificity of NovM was investigated. A test of four aglycon analogues and over 40 nucleotide sugars revealed NovM has a surprisingly stringent substrate specificity and provided only three new "unnatural" natural products. On the basis of the determined substrate specificity, an alternative to the sugar nucleotide biosynthetic dogma and a cautionary note for the general applicability of IVG are introduced.     

Measurement of 2+ 1 level lifetimes in 162Yb and 162Er by fast electronic scintillation timing

Lifetime measurements for the 2⁺ ₁ levels of ¹⁶²Er and ¹⁶²Yb were obtained in β⁺/ɛ decay at the Yale Moving Tape Collector by fast electronic scintillation timing of β⁺γ coincidences. Received: 2 September 2002 / Accepted: 1 October 2002 / Published online: 4 February 2003 RID="a" ID="a"e-mail: mark.caprio@yale.edu Communicated by J. ?yst?     

Transients in the vibrational excitation of cyclobutane decomposition using the variable encounter method

The probability of reaction of cyclobutane molecules in a fixed time interval after experiencing a known variable number of collisions with a hot surface at temperatures between 749 K and 1126 K has been determined using the Variable Encounter Method. Calculations utilizing exponential or gaussian models for energy transfer enable the average amounts of energy transferred for deactivating collisions, <ΔE′?, to be estimated. The exponential model fits the experimental data the best and, using this model, <ΔE′? is 2430 cm^?1 at 749 K and decreases to 1470 cm^?1 at 1126 K. Incubation times are derived from the mean first passage times.     

On the structure of the carbon dioxide dimer

Molecular beam deflection studies of the carbon dioxide dimer indicate a non-polar molecule. This result is shown to be incompatible with the normally accepted T-shaped geometry. Other possible structures are compared and contrasted.     

Deviations from the Curie-Weiss law in the magnetic susceptibility of dilute magnetic alloys

The magnetic susceptibility of dilute magnetic alloys of Mn in Rh and Fe in a Nb-Mo solid solution deviates from the Curie-Weiss law. The following temperature dependence is observed: Δ_χ = C/(T + T_K) + log (T_K/T), with ≡ 0 for T > T_K⁰.