Three coordination compounds of ruthenium(II), belonging to a recently synthesised series of water-soluble compounds of general formula mer-[Ru(L3)(N-N)Cl]Cl, where L3 = 4'-chloro-2,2':6',2″-terpyridine (Cl-tpy), N-N = ethylenediamine (en), 1,2-diaminocyclohexane (dach) or 2,2'-bipyridine (bpy), have shown strong binding to calf thymus DNA and moderate in vitro cytotoxicity towards cancer cell lines. Knowing that serum proteins play a crucial role in the transport and deactivation of ruthenium drugs, we have conducted a detailed study of their interactions with two major metal-transporting serum proteins, albumin and transferrin, and it is presented herein. Ruthenated protein adducts were formed with various concentrations of the three compounds and then separated from the unbound portions by ultrafiltration through 10kDa cut-off centrifugal filter units. The stoichiometry of binding was determined using inductively coupled plasma optical emission spectrometry. One mol of albumin bound up to 7, 8.5 and 1.5mol of compound 1 ([Ru(Cl-tpy)(en)Cl][Cl]), 2 ([Ru(Cl-tpy)(dach)Cl][Cl] and 3 ([Ru(Cl-tpy)(bpy)Cl][Cl]), respectively. One mol of transferrin bound up to 3, 3.5 and 0.4mol of 1, 2 and 3, respectively. The affinity of albumin and transferrin for the three ruthenium compounds was evaluated using fluorescence quenching. The binding constants for 1 and 2 lay within the range 104–105M−1, suggesting moderate-to-strong attachment to albumin. Both compounds showed much lower affinity for transferrin (102–103M−1). Compound 3 bound weakly to each studied protein. High resolution ESI qTOF mass spectra of albumin before and after binding of 1 revealed the high stoichiometry of binding. Although the binding of the compounds 1–3 to albumin and transferrin did not affect proteins’ secondary structure much, their tertiary structures underwent some alterations, as deduced from the circular dichroism study. Changes in the stability of albumin, after binding to compounds 1–3 were examined by differential scanning calorimetry
7 September 2012 in Molecular and Cellular Biochemistry
Metabolic syndrome (MetS) is a complex condition characterized by fat accumulation, dyslipidemia, impaired glucose control and hypertension. In this study, rats were fed a high-fat high-fructose (HFF) diet in order to develop MetS. After ten weeks, the dietary-induced MetS was confirmed by higher body fat percentage, lower HDL-cholesterol and increased blood pressure in the HFF-fed rats compared to the normal-fed control animals. However, the effect of MetS development on the lipidomic signature of the dietary-challenged rats remains to be investigated. To reveal the contribution of specific lipids to the development of MetS, the lipid profiling of rat tissues particularly susceptible to MetS was performed using untargeted UHPLC-QTOF-MS/MS lipidomic analysis. A total of 37 lipid species (mainly phospholipids, triglycerides, sphingolipids, cholesterol esters, and diglycerides) in plasma, 43 lipid species in liver, and 11 lipid species in adipose tissue were identified as dysregulated between the control and MetS groups. Changes in the lipid signature of selected tissues additionally revealed systemic changes in the dietary-induced rat model of MetS.
17 April 2012 in Cellular and Molecular Neurobiology