Isolation and characterization of flavonoids from leaves with vasodilatory and myeloperoxidase-inhibitory activities.

The aim of this study was to perform the isolation and characterization of vasodilatory flavonoids from Aubl. (Annacardiaceae) leaves. In this context, ethyl acetate fraction (EA fraction) was obtained and subjected to fractionation batches by HSCCC affording: myricetin 3---L-rhamnopyranoside (myricitrin, ); quercetin 3--(6"--galloyl)--D-galactopyranoside (); quercetin 3---L-arabinofuranoside (avicularin, ); and quercetin 3---L-rhamnopyranoside (quercitrin, ).

Amyloid-β oligomers induce differential gene expression in adult human brain slices.

Cognitive decline in Alzheimer disease (AD) is increasingly attributed to the neuronal impact of soluble oligomers of the amyloid-β peptide (AβOs). Current knowledge on the molecular and cellular mechanisms underlying the toxicity of AβOs stems largely from rodent-derived cell/tissue culture experiments or from transgenic models of AD, which do not necessarily recapitulate the complexity of the human disease. Here, we used DNA microarray and RT-PCR to investigate changes in transcription in adult human cortical slices exposed to sublethal doses of AβOs.

Conformational plasticity of DM43, a metalloproteinase inhibitor from Didelphis marsupialis: chemical and pressure-induced equilibrium (un)folding studies.

We have investigated the folding of DM43, a homodimeric metalloproteinase inhibitor isolated from the serum of the South American opossum Didelphis marsupialis. Denaturation of the protein induced by GdnHCl (guanidine hydrochloride) was monitored by extrinsic and intrinsic fluorescence spectroscopy. While the equilibrium (un)folding of DM43 followed by tryptophan fluorescence was well described by a cooperative two-state transition, bis-ANS (4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid) fluorescence measurements revealed an intensity maximum at the midpoint of the unfolding transition (2 M GdnHCl), indicating a partially folded intermediate state.

Formation of soluble oligomers and amyloid fibrils with physical properties of the scrapie isoform of the prion protein from the C-terminal domain of recombinant murine prion protein mPrP-(121-231).

Prion diseases are fatal neurodegenerative disorders associated with conformational conversion of the cellular prion protein, PrP(C), into a misfolded, protease-resistant form, PrP(Sc). Here we show, for the first time, the oligomerization and fibrillization of the C-terminal domain of murine PrP, mPrP-(121-231), which lacks the entire unstructured N-terminal domain of the protein. In particular, the construct we used lacks amino acid residues 106-120 from the so-called amyloidogenic core of PrP (residues 106-126).

Folding intermediates of the prion protein stabilized by hydrostatic pressure and low temperature.

Prion diseases are associated with conformational conversion of the cellular prion protein, PrPC, into a misfolded form, PrPSc. We have investigated the equilibrium unfolding of the structured domain of recombinant murine prion protein, comprising residues 121-231 (mPrP-(121-231)). The equilibrium unfolding of mPrP-(121-231) by urea monitored by intrinsic fluorescence and circular dichroism (CD) spectroscopies indicated a two-state transition, without detectable folding intermediates.

Equilibrium unfolding and conformational plasticity of troponin I and T.

The structures and stabilities of recombinant chicken muscle troponin I (TnI) and T (TnT) were investigated by a combination of bis-ANS binding and equilibrium unfolding studies. Unlike most folded proteins, isolated TnI and TnT bind the hydrophobic fluorescent probe bis-ANS, indicating the existence of solvent-exposed hydrophobic domains in their structures. Bis-ANS binding to binary or ternary mixtures of TnI, TnT and troponin C (TnC) in solution is significantly lower than binding to the isolated subunits, which can be explained by burial of previously exposed hydrophobic domains upon association of the subunits to form the native troponin complex.