Metal incorporation in modified PNA duplexes

Substitution of bipyridine for a nucleobase leads to modified peptide nucleic acid (PNA) single strands that are bridged in the presence of Ni2+ into a duplex containing a combination of hydrogen and coordinative bonds. CD experiments demonstrate that the duplex adopts a structure similar to that of an unmodified 10-bp PNA duplex, and UV melting experiments show a very sensitive dependence of the duplex stability on the substitution of a nucleobase pair with a pair of ligands or a metal-ligand alternative base pair.     

-algebras that are only weakly semiprojective

We show that the -algebra of continuous functions on the Cantor set is a weakly semiprojective -algebra that is not semiprojective.

     

Tris(1,10‐phenanthroline‐κ2N,N′)cobalt(III) tris(trifluoromethanesulfonate) dihydrate

The title compound, [Co(C₁₂H₈N₂)₃](CF₃SO₃)₃·2H₂O, crystallizes to form infinite chains of complex cations that are connected through offset face‐to‐face and edge‐to‐face interactions between their phenanthroline ligands. The chains are themselves interconnected through weak offset face‐to‐face ligand interactions. The three trifluoromethanesulfonate anions of the asymmetric unit are connected with one another through the two water molecules by hydrogen bonds. One of the trifluoromethanesulfonate anions is described by a disorder over three positions, with occupancies of 0.35, 0.35 and 0.3 in the refined model.     

Fluorescence labelling of carbohydrates with 2-aminobenzamide (2AB)

2-Aminobenzamide (2AB) is a common fluorescence label attached to reducing oligosaccharides by a reductive amination procedure. Chemical investigation of the published literature procedure reveals labelling occurs by the expected mechanism for both protected and unprotected glucose derivatives to yield open-chain carbohydrates rather than result in the formation of any heterocyclic materials. Pentenyl glucosides may also be readily attached to the 2AB label by a sequence of dihydroxylation, periodate cleavage and subsequent reductive amination of the resulting aldehyde. 2AB labelling is compatible with deprotection of both acetate and benzyl protecting groups.     

First crystal structure studies of CaAlH5

A new member of the aluminum hydride family, CaAlH5, is formed during the decomposition of Ca(AlH4)2. The crystal structure of this new compound was calculated by density functional theory band-structure calculations and confirmed by X-ray powder diffraction analysis. The structure crystallizes in space group P2(1)/n (No. 14), with a = 8.3797(9) angstroms, b = 6.9293(8) angstroms, c = 9.8138(11) angstroms, beta = 93.78(1) degrees, and Z = 8.     

Automated mass spectrometry imaging with a matrix-assisted laser desorption ionization time-of-flight instrument

The automated use of a matrix-assisted laser desorption ionization (MALDI) mass spectrometer (MS) is described for image analysis of samples through implementation of new software for instrument control, data acquisition, and data analysis. The software permits automated acquisition of MS MALDI spectra to form an ordered data array and contains display features to provide images at one or more mass-to-charge ratio values. The technique can be used to scan tissue samples, blotted samples, gels, or other sample surfaces where the image analysis of that sample is required. The program achieves a time of typically 1 s per image point, permitting an analysis made up of large numbers of points with high spatial resolution up to 850 dpi. The features of the software are demonstrated in this paper with samples of printed images, where visible images can be compared to those obtained by mass spectrometry. Quantitative aspects are introduced by analyzing a series of sample spots containing different amounts of several proteins.