Polyanion induced circular dichroism of Thioflavin T.

Thioflavin T (ThT) is amyloid specific fluorescence dye possessing the properties of molecular rotor. We have shown that Thioflavin T forms complexes with non-peptide polyanions heparin, polyadenylate and polystyrene sulphonate by means of absorption spectroscopy. In the presence of chiral polyanions - heparin and polyadenylate - induced optical activity of ThT occurs whereas interaction with achiral polystyrene sulphonate (PSS) does not lead to production of induced circular dichroism signal.

Effect of Fe(3)O(4) magnetic nanoparticles on lysozyme amyloid aggregation.

Peptide amyloid aggregation is a hallmark of several human pathologies termed amyloid diseases. We have investigated the effect of electrostatically stabilized magnetic nanoparticles of Fe(3)O(4) on the amyloid aggregation of lysozyme, as a prototypical amyloidogenic protein. Thioflavin T fluorescence assay and atomic force microscopy were used for monitoring the inhibiting and disassembly activity of magnetic nanoparticles of Fe(3)O(4).

Acridine derivatives inhibit lysozyme aggregation.

We have screened a library of structurally distinct acridine derivatives (19 compounds) for their ability to inhibit lysozyme amyloid aggregation in vitro. Studied acridines were divided into three structurally different groups depending on the molecule planarity and type of the side chain-planar acridines, spiroacridines and tetrahydroacridines. Thioflavine T fluorescence assay and transmission electron microscopy were used for monitoring the inhibiting activity of acridines.

Spectral and kinetic equivalence of oxidized cytochrome C oxidase as isolated and "activated" by reoxidation.

The spectral and kinetic characteristics of two oxidized states of bovine heart cytochrome c oxidase (CcO) have been compared. The first is the oxidized state of enzyme isolated in the fast form (O) and the second is the form that is obtained immediately after oxidation of fully reduced CcO with O2 (OH). No observable differences were found between O and OH states in: (i) the rate of anaerobic reduction of heme a3 for both the detergent-solubilized enzyme and for enzyme embedded in its natural membraneous environment, (ii) the one-electron distribution between heme a3 and CuB in the course of the full anaerobic reduction, (iii) the optical and (iv) EPR spectra.

Specific volume and compressibility of human serum albumin-polyanion complexes.

The ultrasound velocimetry, densitometry, and differential scanning calorimetry have been used to study the formation of the complexes between human serum albumin (HSA) and polyanions heparin (HEP) and/or dextran sulfate (DS). The values of the ultrasound velocity and specific volume allowed us to determine the specific adiabatic compressibility, phi(K)/beta(0), which reflects the degree of volume compressibility of the complexes. We showed that in the presence of HEP and DS the adiabatic compressibility of HSA decreases with increasing concentration of polyanions.

Effect of varying polyglutamate chain length on the structure and stability of ferricytochrome c.

The effect of varying polyglutamate chain length on local and global stability of horse heart ferricytochrome c was studied using scanning calorimetry and spectroscopy methods. Spectral data indicate that polyglutamate chain lengths equal or greater than eight monomer units significantly change the apparent pK(a) for the alkaline transition of cytochrome c. The change in pK(a) is comparable to the value when cytochrome c is complexed with cytochrome bc(1).