Lilianna Trynda-Lemiesz

Studies on the interactions between human serum albumin and trans-indazolium (bisindazole) tetrachlororuthenate(III)

The interactions between HInd[RuInd2Cl4] and human serum albumin have been investigated through UV-Vis, circular dichroism (CD), fluorescence spectroscopy and the inductively coupled plasma-atomic emission spectroscopy (ICP(AES)) method. Binding of Ru(III)-indazole species to albumin has strong impact on protein structure and it influences considerably albumin binding of other molecules like warfarin, heme or metal ions. The metal complex-human serum albumin (HAS) interactions cause conformational changes with loss of helical stability of the protein and local perturbation in the domain IIA binding pocket. The relative fluorescence intensity of the ruthenium-bound HSA decreased, suggesting that perturbation around the Trp 214 residue took place. This was confirmed by the destabilization of the warfarin-binding site, which includes Trp 214, observed in the metal-bound HSA.

Studies on the interactions between human serum albumin and imidazolium [trans-tetrachlorobis(imidazol)ruthenate(III)]

The interactions between imidazolium [trans-tetrachlorobis(imidazol) ruthenate(III)] (Ru-im) and human serum albumin (HSA) have been investigated through UV-Vis, CD, fluorescence spectroscopy and by the antibody precipitation test. Binding of Ru(III)-imidazole species to albumin has a strong impact on the protein structure and influences considerably the albumin binding of other molecules such as warfarin or heme. The metal complex-HSA interactions cause conformational changes with the loss of helical stability of the protein and local perturbation in the domain IIA binding pocket. The relative fluorescence intensity of the ruthenium-bound HSA decreased, suggesting that perturbation around the Trp 214 residue took place. This was confirmed by the destabilisation of the warfarin binding site which includes Trp 214, observed in the metal-bound HSA.

Effect of cis-, trans-diamminedichloroplatinum(II) and DBP on human serum albumin

Both isomers of diamminedichloroplatinum(II) bind to albumin and induce the formation of the albumin dimer (MW approximately 140 kDa). The trans isomer exhibits a much greater tendency to induce a protein dimerization than the cis isomer. Under similar experimental conditions, the phosphonic derivative of diammineplatinum(II) (DBP) does not induce any dimer formation. The amount of bound complex per mol of human serum albumin (HSA, for an incubation time of 7 days) was found to be 6, 10.5 and 1 mol for cis-, trans-DDP and DBP, respectively. The relative fluorescence intensity of platinum-bound HSA decreases to about 55% for cis-DDP, 45% for trans-DDP and to 85% for DBP when compared to the complex-free protein, suggesting that the binding occurs in the proximity of the Trp214 residue. The structural studies (CD) have shown that only DDP-isomers cause the distinct modification of HSA native structure (alpha-helical content). Pt(II) complexes binding to HSA affect the affinity of HSA towards heme and bilirubin. High excess of DDP prevents the heme and bilirubin binding, while DBP affects this binding much less effectively due to the low amount of the protein-bound complex. Reactions of platinum complexes with albumin are believed to play an important role in the metabolism of this anticancer drug. The minor effect of DBP on HSA may indicate that the toxicity of the phosphonate analog is much lower than toxicities of DDP isomers, most likely due to kinetic reasons.

Studies on the interaction between human serum albumin and [Rh2(OAc)2(bpy)2(H2O)2](OAc)2

Absorption, CD, fluorescence, and ICP(AES) methods were used to evaluate the interaction of [Rh2(OAc)2(bpy)2(H2O)2](OAc)2 with human serum albumin (HSA). The rhodium complex reacts easily with HSA; the Rh atoms are coordinated to protein via the imidazole rings of His residues. When the protein was incubated for 24 h at 37 degrees C, the amount of rhodium was found to be approximately 7 mol per mol of HSA. Analysis of CD spectra showed the decreasing helix content to be about 15% in the metal-bound HSA. The relative fluorescence intensity of HSA bound with rhodium decreased to 20% of that of the native state, suggesting that perturbation around the Trp-214 residue took place. This was confirmed by the destruction of the warfarin binding site. The rhodium binding weakens the interaction of HSA with other molecules like heme or bilirubin.

Some aspect of the interactions of adriamycin with human serum albumin

The interaction of adriamycin with human serum albumin (HSA) has been studied by absorption, CD, fluorescence spectroscopy, and quantitative precipitating HSA-antibody test. Our results demonstrate that adriamycin react with HSA and the binding to the protein molecule has a very distinct influence on the stability of ADR in aqueous solutions. The drug molecule binds protein as a monomer. The structural studies have shown the conformational change of HSA modified by adriamycin. The binding of ADR lowers the helicity of the native protein of ca. 15% and ca. 10% in the case of acHSA. The quantitative precipitating test supports distinct changes in the conformation upon ADR binding that decreases the ability of HSA to precipitate with its antibody.

Interaction of Cis- and Trans-RuCl (2)(DMSO)(4) With Human Serum Albumin.

The interaction between cis- and trans- RuCl2(DMSO)4 and human serum albumin have been investigated through UV-Vis, circular dichroism, fluorescence spectroscopy and inductively couplet plasma atomic emission spectroscopy (ICP(AES)) method Albumin can specifically bind 1 mole of cis-isomer and 2 moles of the trans-isomer RuCl2(DMSO)4 complex. The interaction of RuCl2(DMSO)4 with HSA causes: a conformational change with the loss of helical stability of protein; the strong quenching of the Trp 214 fluorescence indicating that the conformational change of the hydrophobic binding pocked in subdomain IIA takes place; a local perturbation of the warfarin binding site and induce some conformational changes at neighbour domains, a changing of the binding abilities towards heme.