Fast and quantitative high-performance liquid chromatography method for the determination of 9-fluorenylmethoxycarbonyl release from solid-phase synthesis resins

C-terminal tetrapeptides inhibit Aβ42-induced neurotoxicity primarily through specific interaction at the N-terminus of Aβ42

Inhibition of amyloid β-protein (Aβ)-induced toxicity is a promising therapeutic strategy for Alzheimer's disease (AD). Previously, we reported that the C-terminal tetrapeptide Aβ(39-42) is a potent inhibitor of neurotoxicity caused by Aβ42, the form of Aβ most closely associated with AD. Here, initial structure-activity relationship studies identified key structural requirements, including chirality, side-chain structure, and a free N-terminus, which control Aβ(39-42) inhibitory activity. To elucidate the binding site(s) of Aβ(39-42) on Aβ42, we used intrinsic tyrosine (Y) fluorescence and solution-state NMR. The data suggest that Aβ(39-42) binds at several sites, of which the predominant one is located in the N-terminus of Aβ42, in agreement with recent modeling predictions. Thus, despite the small size of Aβ(39-42) and the hydrophobic, aliphatic nature of all four side-chains, the interaction of Aβ(39-42) with Aβ42 is controlled by specific intermolecular contacts requiring a combination of hydrophobic and electrostatic interactions and a particular stereochemistry.

Molecular modeling and epitopes mapping of human adenovirus type 3 hexon protein

The hexon protein of human adenovirus (HAdV) processes type-specific B-cell neutralizing epitopes. We developed a new effective, reliable approach to map these epitopes on hexon protein of HAdVs. A three-dimensional (3D) model of the HAdV3 hexon was obtained by homology modeling and refined by molecular mechanics and molecular dynamics simulations. A modified evolutionary trace (ET) analysis called reverse ET (RET) was used to predict the type-specific B-cell neutralizing epitopes. An epitope-screening algorithm based on analyzing the solvent accessibility surface (SAS) area from the 3D model and calculation of sites homology using RET was designed and implemented in the BioPerl script language. Five epitope polypeptide segments were predicted and mapped onto the 3D model. Finally five polypeptides were synthesized and the predicted epitopes were identified by enzyme-linked immunosorbent assay (ELISA) and Neutralization Test (NT). It was found that the type-specific neutralizing epitopes of HAdV3 are located at the top surface of hexon tower regions (residue numbers: 135-146, 169-178, 237-251, 262-272, 420-434). This work is of great significance to the molecular design of a multivalent HAdVs vaccine.

Polystyrene-graft-Polyglycerol Resins: A New Type of High-Loading Hybrid Support for Organic Synthesis

The preparation of a dendritic graft polymer by a very efficient synthesis of polyglycerol directly on a polystyrene resin is presented. This one-step process can be performed on a multigram scale to provide a chemically stable polymeric support. The resulting hybrid polymers were fully characterized by diverse analytical methods (NMR, IR, ESEM, UV detection of cleaved protecting groups, and mass-spectrometric methods). They combine a high loading capacity (up to 4.3 mmol g(-1)) with good swelling properties in a wide range of solvents (including water), which is the major drawback for many existing solid phase supports. In comparison to the widely employed PEGylated resins, these hybrid materials offer a 10-fold higher loading capacity. Their suitability as supports for organic synthesis and for the immobilization of reagents has been demonstrated. These materials also swell in water, and consequently, it should be possible to use these new hybrid materials for synthesis in protic solvents.

Quantitative Determination of Resin Loading in Solid-Phase Organic Synthesis Using (13)C MAS NMR

The use of quantitative carbon nuclear magnetic resonance spectroscopy ((13)C NMR) for the determination of resin loadings has been investigated. Magic angle spinning (MAS) NMR spectra have been obtained for solvent-swollen resins on a conventional 7 mm CP/MAS probe using the two pulse phase modulation (TPPM) proton decoupling sequence. Loadings of resin-bound organic compounds were evaluated via addition of tetrakis(trimethylsilyl)silane as reference or using the carbon resonances of the polymeric resin material as an internal standard. Results for several functionalized Wang and trityl resins are consistent with those obtained using well-established analytical methods. The (13)C NMR method has interesting applications in the field of solid-phase organic synthesis (SPOS), since no functional group acting as a support for the attachment of a quantifiable chromophore must be available in the material of interest.