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Kinetics of Denaturation of Human and Chicken Hemoglobins in the Presence of Co-solvents
Ajloo, Davood,Moosavi-Movahedi, Ali A. Korean Society for Biochemistry and Molecular Biol 2003 Journal of biochemistry and molecular biology Vol.36 No.4
The stability of four hemoglobins (Hb) in dimer forms (low concentration) were investigated by the kinetics of denaturation. The rate constants of denaturation were obtained by variation of 280 nm absorption versus time in 10 mM Tris-HCl, 10 mM EDTA, pH 8.0 at $45^{\circ}C$ in the absence and presence of 0.5 M ethanol, dimethyl sulfoxide (DMSO), formamide, and glycerol. The results show the trend of rate constants in different co-solvents in the following order: chicken hemolysate < human hemolysate and chicken Hb D < chicken Hb A. The buried surface area was calculated for Hb samples in the absence of cosolvents. Accordingly, the trend points out that: chicken Hb D > chicken Hb A > human Hb A. These results suggest that both chicken hemolysate and chicken Hb D are relatively more stable than human and chicken Hb A, respectively. However, the denaturation rate constants of Hb in different co-solvents have designated the following order: ethanol > DMSO > formamide > glycerol. As a matter of fact, this phenomenon is an indication of an increase in the denaturation capacity (DC) and hydrophobicity, and a decrease in the surface tension of the solution in the preceding co-solvents.
Bordbar, A.K.,Ghaderi, A.R.,Safaei, E.,Tangestaninejad, S.,Eslami, A.,Saboury, A.A.,Moosavi Movahedi, A.A. Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.5
In the present work, the interaction of three water soluble porphyrins, tetra(p-trimethyle) ammonium phenyl porphyrin iodide (TAPP) as a cationic porphyrin, tetra sodium meso-tetrakis (p-sulphonato phenyle) porphyrin (TSPP) as an anionic porphyrin and manganese tetrakis (p-sulphonato phenyl) porphinato acetate (MnTSPP) as a metal porphyrin, with histone H₂B have been studied by isothermal titration microcalorimetry at 8 mM phosphate buffer, pH 6.8 and 27 °C. The values of binding constant, entropy, enthalpy and Gibbs free energy changes for binding of the first MnTSPP, and first and second TSPP and TAPP molecules were estimated from microcalorimetric data analysis. The results represent that the process is both entropy and enthalpy driven and histone induces self-aggregation of the porphyrins. The results indicate that both columbic and hydrophobic interactions act as self-aggregation driving forces for the formation of aggregates around histone.
Electrochemical Behavior of Redox Proteins Immobilized on Nafion-Riboflavin Modified Gold Electrode
S. Rezaei-Zarchi,A. A. Saboury*,J. Hong,P. Norouzi,A. B. Moghaddam,H. Ghourchian,M. R. Ganjali,A. A. Moosavi-Movahedi,A. Javed,A. Mohammadian 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.12
Electron transfer of a redox protein at a bare gold electrode is too slow to observe the redox peaks. A novel Nafion-riboflavin functional membrane was constructed during this study and electron transfer of cytochrome c, superoxide dismutase, and hemoglobin were carried out on the functional membrane-modified gold electrode with good stability and repeatability. The immobilized protein-modified electrodes showed quasi-reversible electrochemical redox behaviors with formal potentials of 0.150, 0.175, and 0.202 V versus Ag/AgCl for the cytochrome c, superoxide dismutase and hemoglobin, respectively. Whole experiment was carried out in the 50 mM MOPS buffer solution with pH 6.0 at 25 oC. For the immobilized protein, the cathodic transfer coefficients were 0.67, 0.68 and 0.67 and electron transfer-rate constants were evaluated to be 2.25, 2.23 and 2.5 s-1, respectively. Hydrogen peroxide concentration was measured by the peroxidase activity of hemoglobin and our experiment revealed that the enzyme was fully functional while immobilized on the Nafion-riboflavin membrane.
Electrochemical Behavior of Redox Proteins Immobilized on Nafion-Riboflavin Modified Gold Electrode
Rezaei-Zarchi, S.,Saboury, A.A.,Hong, J.,Norouzi, P.,Moghaddam, A.B.,Ghourchian, H.,Ganjali, M.R.,Moosavi-Movahedi, A.A.,Javed, A.,Mohammadian, A. Korean Chemical Society 2007 Bulletin of the Korean Chemical Society Vol.28 No.12
Electron transfer of a redox protein at a bare gold electrode is too slow to observe the redox peaks. A novel Nafion-riboflavin functional membrane was constructed during this study and electron transfer of cytochrome c, superoxide dismutase, and hemoglobin were carried out on the functional membrane-modified gold electrode with good stability and repeatability. The immobilized protein-modified electrodes showed quasireversible electrochemical redox behaviors with formal potentials of 0.150, 0.175, and 0.202 V versus Ag/AgCl for the cytochrome c, superoxide dismutase and hemoglobin, respectively. Whole experiment was carried out in the 50 mM MOPS buffer solution with pH 6.0 at 25 oC. For the immobilized protein, the cathodic transfer coefficients were 0.67, 0.68 and 0.67 and electron transfer-rate constants were evaluated to be 2.25, 2.23 and 2.5 s?1, respectively. Hydrogen peroxide concentration was measured by the peroxidase activity of hemoglobin and our experiment revealed that the enzyme was fully functional while immobilized on the Nafion-riboflavin membrane.
Bordbar, A.K.,Nasehzadeh, A.,Ajloo, D.,Omidiyan, K.,Naghibi, H.,Mehrabi, M.,Khajehpour, H.,Rezaei-Tavirani, M.,Moosavi-Movahedi, A.A. Korean Chemical Society 2002 Bulletin of the Korean Chemical Society Vol.23 No.8
Binding of dodecyl trimethylammonium bromide (DTAB) to human and bovine hemoglobin and globin samples has been investigated in 50 mM glycine buffer pH = 10, I = 0.0318 and 300 K by equilibrium dialysis and temperature scanning spectrophotometry techniques and method for calculation of average hydrophobicity. The binding data has been analyzed, in terms of binding capacity concept $({\theta})$, Hill coefficient (nH) and intrinsic Gibbs free energy of binding $({\Delta}Gbv).$ The results of binding data, melting point (Tm) and average hydrophobicity show that human hemoglobin has more structural stability than bovine hemoglobin sample. Moreover the results of binding data analysis represent the systems with two and one sets of binding sites for hemoglobin and globin, respectively. It seems that the destabilization of hemoglobin structure due to removal of heme group, is responsible of such behavior. The results indicating the removal of heme group from hemoglobin caused the depletion of first binding set as an electrostatic site upon interaction with DTAB and exposing the hydrophobic patches for protein.
Thermodynamic and Structural Studies on the Human Serum Albumin in the Presence of a Polyoxometalate
Ajloo, D.,Behnam, H.,Saboury, A.A.,Mohamadi-Zonoz, F.,Ranjbar, B.,Moosavi-Movahedi, A.A.,Hasani, Z.,Alizadeh, K.,Gharanfoli, M.,Amani, M. Korean Chemical Society 2007 Bulletin of the Korean Chemical Society Vol.28 No.5
The interaction of a polyoxometal (POM), K6SiW11Co(H2O)O39.10H2O (K6) as a Keggin, with human serum albumin (HSA) was studied by different methods and techniques. Binding studies show two sets of binding sites for interaction of POM to HSA. Binding analysis and isothermal calorimetery revealed that, the first set of binding site has lower number of bound ligand per mole of protein (ν), lower Hill constant (n), higher binding constant (K), more negative entropy (ΔS) and more electrostatic interaction in comparison to the second set of binding site. In addition, differential scanning calorimetery (DSC) and spectrophotometery data showed that, there are two energetic domains. The first domain is less stable (lower Tm and Cp) which corresponds to the tail segment of HSA and another with more stability is related to the head segment of HSA. Polyoxometal also decreases the stability of protein as Tm, secondary and tertiary structure as well as quenching of the fluorescence decrease. On other hand, perturbations in tertiary structure are more than secondary structure.
Thermodynamic and Structural Studies on the Human Serum Albumin in the Presence of a Polyoxometalate
D. Ajloo,H. Behnam,A. A. Saboury,F. Mohamadi-Zonoz,B. Ranjbar,A. A. Moosavi-Movahedi,Z. Hasani,K. Alizadeh,M. Gharanfoli,M. Amani 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.5
The interaction of a polyoxometal (POM), K6SiW11Co(H2O)O39.10H2O (K6) as a Keggin, with human serum albumin (HSA) was studied by different methods and techniques. Binding studies show two sets of binding sites for interaction of POM to HSA. Binding analysis and isothermal calorimetery revealed that, the first set of binding site has lower number of bound ligand per mole of protein (n), lower Hill constant (n), higher binding constant (K), more negative entropy (DS) and more electrostatic interaction in comparison to the second set of binding site. In addition, differential scanning calorimetery (DSC) and spectrophotometery data showed that, there are two energetic domains. The first domain is less stable (lower Tm and Cp) which corresponds to the tail segment of HSA and another with more stability is related to the head segment of HSA. Polyoxometal also decreases the stability of protein as Tm, secondary and tertiary structure as well as quenching of the fluorescence decrease. On other hand, perturbations in tertiary structure are more than secondary structure.