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Conformational Lock and Dissociative Thermal Inactivation of Lentil Seedling Amine Oxidase
Moosavi-Nejad, S. Zahra,Moosavi-Movahedi, Ali-Akbar,Rezaei-Tavirani, Mostafa,Floris, Giovanni,Medda, Rosaria Korean Society for Biochemistry and Molecular Biol 2003 Journal of biochemistry and molecular biology Vol.36 No.2
The kinetics of thermal inactivation of copper-containing amine oxidase from lentil seedlings were studied in a 100 mM potassium phosphate buffer, pH 7, using putrescine as the substrate. The temperature range was between $47-60^{\circ}C$. The thermal inactivation curves were not linear at 52 and $57^{\circ}C$; three linear phases were shown. The first phase gave some information about the number of dimeric forms of the enzyme that were induced by the higher temperatures using the "conformational lock" pertaining theory to oligomeric enzyme. The "conformational lock" caused two additional dimeric forms of the enzyme when the temperature increased to $57^{\circ}C$. The second and third phases were interpreted according to a dissociative thermal inactivation model. These phases showed that lentil amine oxidase was reversibly-dissociated before the irreversible thermal inactivation. Although lentil amine oxidase is not a thermostable enzyme, its dimeric structure can form "conformational lock," conferring a structural tolerance to the enzyme against heat stress.
Conformational Lock and Dissociative Thermal Inactivation of Lentil Seedling Amine Oxidase
( S. Zahra Moosavi Nejad ),( Ali Akbar Moosavi Movahedi ),( Mostafa Rezaei Tavirani ),( Giovanni Floris ),( Rosaria Medda ) 생화학분자생물학회 2003 BMB Reports Vol.36 No.2
The kinetics of thermal inactivation of copper-containing amine oxidase from lentil seedlings were studied in a 100 mM potassium phosphate buffer, pH 7, using putrescine as the substrate. The temperature range was between 47-60℃. The thermal inactivation curves were not linear at 52 and 57℃; three linear phases were shown. The first phase gave some information about the number of dimeric forms of the enzyme that were induced by the higher temperatures using the conformational lock pertaining theory to oligomeric enzyme. The conformational lock caused two additional dimeric forms of the enzyme when the temperature increased to 50℃. The second and third phases were interpreted according to a dissociative thermal inactivation model. These phases showed that lentil amine oxidase was reversibly-dissociated before the irreversible thermal inactivation. Although lentil amine oxidase is not a thermostable enzyme, its dimeric structure can form conformational lock, conferring a structural tolerance to the enzyme against heat stress.
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.
Thermal Dissociation and Conformational Lock of Superoxide Dismutase
Hong, J.,Moosavi-Movahedi, A.A.,Ghourchian, H.,Amani, M.,Amanlou, M.,Chilaka, F.C. Korean Society for Biochemistry and Molecular Biol 2005 Journal of biochemistry and molecular biology Vol.38 No.5
The kinetics of thermal dissociation of superoxide dismutase (SOD) was studied in 0.05 M Tris-HCl buffer at pH 7.4 containing $10^{-4}\;M$ EDTA. The number of conformational locks and contact areas and amino acid residues of dimers of SOD were obtained by kinetic analysis and biochemical calculation. The cleavage bonds between dimers of SOD during thermal dissociation and type of interactions between specific amino acid residues were also simulated. Two identical contact areas between two subunits were identified. Cleavage of these contact areas resulted in dissociation of the subunits, with destruction of the active centers, and thus, lost of activity. It is suggested that the contact areas interact with active centers by conformational changes involving secondary structural elements.
Inhibition of Human Hemoglobin Autoxidation by Sodium n - Dodecyl Sulphate
(Dayer Mohammad Reza),(Moosavi Movahedi Ali Akbar),(Norouzi Parviz),(Ghourchian),(Hedayat Olah),(Safarian Shahrokh) 생화학분자생물학회 2002 BMB Reports Vol.35 No.4
The effect of sodium n-dodecyl sulphate (SDS) on hemoglobin autoxidation was studied in the presence of a 100 mM phosphate buffer (pH 7.0) by different methods. These included spectrophotometry, fluorescence technique, cyclic voltametry, differential scanning calorimetry, and densitometry. Spectroscopic studies showed that SDS concentrations up to 1 mM increased deoxy-, decreases oxy-, and had no significant effect on the met- conformation of hemoglobin. Therefore, a SDS concentration up to 1 mM increased the deoxy form of hemoglobin as the folded, compact state and decreases the oxy conformation. The turbidity measurements and differential scanning calorimetry techniques indicated a more stable conformation for hemoglobin in the presence of SDS up to 1 mM. Electrochemical studies also confirmed a more difficult oxidation under these conditions. The induction of the deoxy form in the presence of SDS was confirmed by densitometry techniques. The compact structure of deoxyhemoglobin blocks the formation of met-conformation in low SDS concentrations.
Inhibition of Human Hemoglobin Autoxidaiton by Sodium n-Dodecyl Sulphate
Reza, Dayer Mohammad,Ali Akbar, Moosavi-Movahedi,Parviz, Norouzi,Ghourchian, Ghourchian,Hedayat-Olah, Hedayat-Olah,Shahrokh, Safarian 생화학분자생물학회 2002 Journal of biochemistry and molecular biology Vol.35 No.4
The effect of sodium n-dodecyl sulphate (SDS) on hemoglobin autoxidation was studied in the presence of a 100mM phosphate buffer (pH 7.0) by different methods. These included spectorphotometry, fluorescence technique, cyclic voltametry, differential scanning calorimetry, and densitometry. Spectroscopic studies showed that SDS concentrations up to 1 mM increased deoxy-, decreases oxy-, and had no significant effect on the met- conformation of hemoglobin. Therefore, a SDS concentration up to 1 mM increased the deoxy form of hemoglobin as the folded, compact state and decreases the oxy conformation. The turbidity measurements and differential scanning calorimetry techniques indicated a more stable conformation for hemoglobin in the presence of SDS up to 1mM. Electrochemical studies also confirmed a more difficult oxidation under these conditions. The induction of the deoxy form in the presence of SDS was confirmed by densitometry techniques. The compact structure of deoxyhemoglobin blocks the formation of met-conformation in low SDS concentrations.
A Product Inhibition Study on Adenosine Deaminase by Spectroscopy and Calorimetry
(Ali Akbar Saboury),(Ghasem Ataie Jafari),(Ali Akbar Moosavi Movahedi),(Mohammad Reza Housaindokht),(Gholam Hosain Hakimelahi),(Adeleh Divsalar) 생화학분자생물학회 2002 BMB Reports Vol.35 No.3
Kinetic and thermodynamic studies have been made on the effect of the inosine product on the activity of adenosine deaminase in a 50 mM sodium phosphate buffer, pH 7.5, at 27oC using UV spectrophotometry and isothermal titration calorimetry (ITC). A competitive inhibition was observed for inosine as a product of the enzymatic reaction. A graphical-fitting method was used for determination of the binding constant and enthalpy of inhibitor binding by using isothermal titration microcalorimetry data. The dissociation-binding constant is equal to 140 μM by the microcalorimetry method, which agrees well with the value of 143 μM for the inhibition constant that was obtained from the spectroscopy method.
A Product Inhibition Study on Adenosine Deaminase by Spectroscopy and Calorimetry
Saboury, Ali Akbar,Divsalar, Adeleh,Jafari, Ghasem Ataie,Moosavi-Movahedi, Ali Akbar,Housaindokht, Mohammad Reza,Hakimelahi, Hosain 생화학분자생물학회 2002 Journal of biochemistry and molecular biology Vol.35 No.3
Kinetic and thermodynamic studies have been made on the effect of the inosine product on the activity of adenosine deaminase in a 50 mM sodium phosphate buffer, pH 7.5, at $27^{\circ}C$ using UV spectrophotometry and isothermal titration calorimetry (ITC). A competitive inhibition was observed for inosine as a product of the enzymatic reaction. A graphical-fitting method was used for determination of the binding constant and enthalpy of inhibitor binding by using isothermal titration microcalorimetry data. The dissociation-binding constant is equal to $140\;{\mu}M$ by the microcalorimetry method, which agrees well with the value of $143\;{\mu}M$ for the inhibition constant that was obtained from the spectroscopy method.