Use of 19F NMR spectroscopy to screen chemical libraries for ligands that bind to proteins

Identification of compounds from chemical libraries that bind to macromolecules by use of NMR spectroscopy has gained increasing importance during recent years. A simple methodology based on (19)F NMR spectroscopy for the screening of ligands that bind to proteins, which also provides qualitative information about relative binding strengths and the presence of multiple binding sites, is presented here. A library of fluorinated compounds was assembled and investigated for binding to the two bacterial chaperones PapD and FimC, and also to human serum albumin (HSA). It was found that library members which are bound to a target protein could be identified directly from line broadening and/or induced chemical shifts in a single, one-dimensional (19)F NMR spectrum. The results obtained for binding to PapD using (19)F NMR spectroscopy agreed well with independent studies based on surface plasmon resonance, providing support for the versatility and accuracy of the technique. When the library was titrated to a solution of PapD chemical shift and linewidth changes were observed with increasing ligand concentration, which indicated the presence of several binding sites on PapD and enabled the assessment of relative binding strengths for the different ligands. Screening by (19)F NMR spectroscopy should thus be a valuable addition to existing NMR techniques for evaluation of chemical libraries in bioorganic and medicinal chemistry.     

Maximally aligned states in 99Ag

Excited states of ⁹⁹Ag were populated via the ⁵⁰Cr + ⁵⁸Ni (261 MeV) reaction using the NORDBALL detector array equipped with charged-particle and neutron detector systems for reaction channel separation. On the basis of the measured γγ-coincidence relations and angular distribution ratios a significantly extended level scheme has been constructed up to E _x ∼ 7.8 MeV and I = 35/2. The experimental results were described within the framework of the shell model. Candidates for states fully aligned in the πg _9/2 ^-3ν(d _5/2, g _7/2)² valence configuration space were found at 4109 and 6265 keV. Received: 18 June 2002 / Accepted: 11 October 2002 / Published online: 4 February 2003 RID="a" ID="a"e-mail: sohler@atomki.hu Communicated by J. ?yst?     

Application of high performance liquid chromatography combined with diode-array detection for analysis of proteins and peptides in human cerebrospinal fluid

Different strategies for HPLC separation, including molecular sieving, ion-exchange, and hydrophobic interaction as well as reversed phase chromatography, were used to study molecular components in human cerebrospinal fluid (CSF). The separations were followed by photodiode-array UV detection, which is a recently developed technique allowing a direct and rapid discrimination between peptides and proteins differing in their content of aromatic amino acids. By the various HPLC techniques in conjunction with diode-array detection it was possible to identify and characterize several protein and peptide components present in CSF. The procedure also allowed quantitative analysis of CSF proteins using minute amounts of the fluid.     

Higher Hopf formulae for homology via Galois Theory

We use Janelidze's Categorical Galois Theory to extend Brown and Ellis's higher Hopf formulae for homology of groups to arbitrary semi-abelian monadic categories. Given such a category A and a chosen Birkhoff subcategory B of A, thus we describe the Barr-Beck derived functors of the reflector of A onto B in terms of centralization of higher extensions. In case A is the category Gp of all groups and B is the category Ab of all abelian groups, this yields a new proof for Brown and Ellis's formulae. We also give explicit formulae in the cases of groups vs. k-nilpotent groups, groups vs. k-solvable groups and precrossed modules vs. crossed modules.     

A type 2 Ferrier rearrangement-based synthesis of d-myo-inositol 1,4,5-trisphosphate

The synthesis of d-myo-inositol 1,4,5-trisphosphate (InsP₃) from methyl α-d-glucopyranose, via a type 2 Ferrier rearrangement is reported. A key intermediate in this synthesis possesses orthogonal protecting groups at the 1-, 4- and 5-position, making it a versatile starting point for the synthesis of unnatural InsP₃ derivatives. Biological evaluation of the synthetic InsP₃ demonstrates that this compound evokes selective Ca²⁺ release via activation of InsP₃ receptors.     

On an algorithm considered by Stieltjes

This paper studies an iterative algorithm of the type of Gauss's algorithm mentioned by Stieltjes in his correspondence with Hermite (lettre 323) and later investigated by Myrberg. In particular, what appears to be a false statement by Stieltjes is corrected. The same algorithm, apparently being unaware of his predecessors, has also been considered by Lehmer.     

Synthesis and characterisation of medium-sized ring systems by oxidative cleavage. Part 2: Insights from the study of ring expanded analogues

Variable temperature NMR analysis and computational methods have been used to develop a detailed understanding of the ¹H NMR spectra of a family of medium-sized ring containing compounds. The family consists of analogues containing 10-, 11- and 12-membered rings and in all cases the NMR spectra at room temperature showed a series of diastereotopic methylene signals despite the lack of a stereogenic centre in these systems. On repeating the NMR analysis at higher temperatures, all the signals coalesced for the 12-membered ring system consistent with full interconversion of ring conformers. This was not observed in the analogous 10- and 11-membered ring systems with the interchange of conformers remaining slow on the NMR timescale. However, 1D gs-NOESY/EXSY NMR experiments showed that in the smaller ring systems interconversion of diastereotopic protons did occur. Computational studies suggest that the dynamic process observed by NMR for the 10- and 11-membered rings systems is different from that observed in the 12-membered ring containing compound.