Local structure and charge distribution in the UO(2)-U(4)O(9) system

Analysis of X-ray absorption fine structure spectra of UO(2+x) for x = 0-0.20 (UO(2)--U(4)O(9)) reveals that the adventitious O atoms are incorporated as oxo groups with U--O distances of 1.74 A, most likely associated with U(VI), that occur in clusters so that the UO(2) fraction of the material largely remains intact. In addition to the formation of some additional longer U--O bonds, the U sublattice consists of an ordered portion that displays the original U--U distance and a spectroscopically silent, glassy part. This is very different from previous models derived from neutron diffraction that maintained long U--O distances and high U--O coordination numbers. UO(2+x) also differs from PuO(2+x) in its substantially shorter An-oxo distances and no sign of stable coordination with H(2)O and its hydrolysis products.     

Precise atomic mass determinations at mass 124

The Manitoba II high-resolution mass spectrometer has been used to determine eight precise atomic mass differences amongst ¹²⁴Sn, ¹²⁴Te, ¹²⁴Xe, ¹³C³⁷Cl₃ and ⁵⁴Fe³⁵Cl₂. Precise values have been derived for the double β- decay energies of ¹²⁴Xe and ¹²⁴Sn and for the masses of ¹²⁴Sn, ¹²⁴Te, ¹²⁴Xe and ⁵⁴Fe. The precision of the mass of ¹²⁴Xe has been improved by a factor of ≈150.     

A New Bacterial Adenosine-Derived Nucleoside as an Example of RNA Modification Damage

The fields of RNA modification and RNA damage both exhibit a plethora of non-canonical nucleoside structures. While RNA modifications have evolved to improve RNA function, the term RNA damage implies detrimental effects. Based on stable isotope labelling and mass spectrometry, we report the identification and characterisation of 2-methylthio-1,N6-ethenoadenosine (ms²ϵA), which is related to 1,N6-ethenoadenine, a lesion resulting from exposure of nucleic acids to alkylating chemicals in vivo. In contrast, a sophisticated isoprene labelling scheme revealed that ms²ϵA biogenesis involves cleavage of a prenyl moiety in the known transfer RNA (tRNA) modification 2-methylthio-N6-isopentenyladenosine (ms²i⁶A). The relative abundance of ms²ϵA in tRNAs from translating ribosomes suggests reduced function in comparison to its parent RNA modification, establishing the nature of the new structure in a newly perceived overlap of the two previously separate fields, namely an RNA modification damage.     

Some developments in the phosphitetriester method for synthesis of oligonucleotides

1,l-Dimethyl-2,2,2-trichloroethyl has merit as a protecting group for P-O in the phosphite-triester synthesis of oligonucleotides. Use of this group enables one to simplify procedures for preparing active nucleoside phosphorochloridite reagents, to remove oligonucleotide phosphotriester intermediates intact from a solid support, and to conduct block syntheses in solution or on a silica support viaphosphite chemistry. Deprotection can be achieved by warming the trihaloethyl phosphotriesters with tributylphosphine. The high efficiency of the coupling and deprotection reactions for oligomers bound to an insoluble support make this chemistry especially attractive.     

Effect of the Irradiation Conditions on the Yield of Hydrogen Peroxide in Frozen Aqueous Solutions of Adenine Derivatives

Russian Journal of Physical Chemistry A - Comparative results are presented from detecting hydrogen peroxide (H2O2) in aqueous solutions of adenine derivatives irradiated at 77 K in the near-UV...