Browsing by Author "Ceylan, H"

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Application of Natural Kaolin as Support for the Immobilization of Catalase From Bovine Liver
(Asian Journal of Chemistry, 2006) Savran, A; Alkan, S; Demir, H; Ceylan, H
Catalase from bovine liver was immobilized on to natural kaolin by physical adsorption method. About 80% of the protein content was immobilized on to support. The activities of immobilized catalase were determined in the reaction mixture containing substrate hydrogen peroxide and free catalase. The effects of reaction temperature, thermostability, stability in organic solvent, leaching and storage studies of immobilized catalase were investigated. Kaolinimmobilized catalase exhibited activities higher by four folds than free catalase after thermal stability test at 70 degrees C. Immobilized catalase was found to be stable in hexane at room temperature up to 12 d and also showed higher stability than free catalase in the storage study. Leaching studies showed that the immobilized catalase remained fully active even after being washed by 20 mL of solvent. The experimental results showed that physical adsorption is suitable for the attachment of enzyme on to kaolin.
Bentonite-Supported Catalase
(Serbian Chemical Soc, 2005) Alkan, S; Ceylan, H; Arslan, O
The properties of the clay bentonite as a support for enzyme immobilization were studied using the enzyme catalase. Such an immobilization does not result in enzyme inactivation and constitutes a valuable method for immobilizing catalase at high ionic strength. The bentonite-supported catalase was characterized in terms of pH and ionic strength dependencies, thermal and storage stability and kinetic parameters. These studies indicate that bentonite is a valuable support for the simple adsorption of enzymes.
Effects of Some Drugs on Enzyme Activity of Catalase From Bovine Liver
(Asian Journal of Chemistry, 2006) Alkan, S; Savran, A; Demir, H; Ceylan, H
The effects of gentamicin sulphate, acetyl salicylic acid, ampicillin sodium, paracetamol, potassium penicillin and augmentin were investigated on the in-vitro enzyme activity of catalase. Catalase (CAT:EC1.11.1.6) was purified from bovine liver by a simple and rapid method. The purification process was done by 2',5'-ADP sepharose 4B affinity chromatography. Although the purified enzyme showed a tetrameric band on sodium dodecyl sulphate polyacryilamide gel electrophrosis but bovine liver showed a one band. The enzyme activity was measured spectrophotometrically at 240 nm, according to the method of Aebi. From these six drugs, paracetamol, potassium penicillin and augmentin inhibited the activity of the purified enzyme; gentamicin sulphate, acetyl salicylic acid and ampicillin sodium showed little effect on the enzyme activity. The 15() values for these three drugs were as 4.6, 0.35 and 0.49 mM, respectively. The K-i constants were 20, 25 and 25 mM, respectively and they were competitive inhibitors.
Evaluation of the Thermodynamic Parameters for the Adsorption of Some Hydrocarbons on Chemically Treated-Bentonites by Inverse Gas Chromatography
(Springer, 2005) Gürkan, R; Ceylan, H; Sahan, T; Savran, A; Kubilay, S
Inverse gas chromatography has been used to evaluate the adsorption parameters (Delta H-a, Delta H-st, Delta S-a and Delta G(a)) of some probe molecules, each representing a class of organic (n-hexane, cyclohexane, benzene, n-octane, 1-octene and isooctane) on bentonite and chemically treated-bentonites. The adsorption parameters of the probes on the bentonite samples were determined in infinite dilution region. Adsorption of the organic species was investigated in the temperature range of 200-275 degrees C, using a flame ionization detector, and nitrogen as a carrier gas. The net retention volumes (V-n) of the probes were determined by the help of the retention times (t(R)) observed on gas chromatograms for each probe. Injection was made at least three times for each probe, obtaining reproducible results of +/- 0.5%. It was found that benzene exhibits more negative Delta H than for n-hexane and cyclohexane on all of the adsorbents. In addition, it was found that 1-octene exhibits more negative Delta H than for n-octane and isooctane on the chemically treated-bentonites, whereas n-octane exhibits more negative Delta H than for 1-octene and isooctane on the natural bentonite. Also, interactions of benzene with the natural- and chemically treated-bentonites were found to be stronger than those of n-hexane and cyclohexane with the same carbon number. Again, interactions of the 1-octene with the chemically treated-bentonites were found to be stronger those of n-octane and isooctane with the same carbon number. On the contrary, interactions of n-octane with the untreated-bentonite were found to be stronger than those of 1-octene and isooctane.
Purification and Characterization of Catalase From Bovine Liver
(indian veterinary Journal, 2006) Demir, H; Savran, A; Alkan, S; Ceylan, H
Removal of Some Heavy Metal Cations From Aqueous Solution by Adsorption Onto Natural Kaolin
(Sage Publications inc, 2005) Ceylan, H; Sahan, T; Gürkan, R; Kubilay, S
The adsorption removal of some heavy metal cations such as Cu(II), Zn(II) and Co(II) from aqueous solution onto kaolin has been studied using the batch method with initial metal ion concentrations within the range 15-70 mg/l. The percentage adsorption and equilibrium concentrations were determined by means of atomic absorption flame photometry as a function of adsorbate concentration, pH and temperature. Ion-exchange studies showed that over the complete concentration range studied the adsorption ratios for metal cations adsorbed onto kaolin correlated with the linear forms of the Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich (DKR) adsorption isotherms. The cation-exchange capacity of kaolin towards each metal ion studied was evaluated. It was found that the adsorption phenomena depended on the charge density and diameter of the hydrated ion. The equilibrium studies demonstrated that the selectivity of the ions followed the sequence Zn(II) > Cu(II) > Co(II) at pH 7.0. Calculation of thermodynamic parameters such as the standard enthalpy (Delta H-0), Gibbs free energy (Delta G(0)) and entropy (Delta S-0) showed that the adsorption of the heavy metal ions studied onto kaolin was an endothermic process which was favoured at higher temperatures. These results show that natural kaolin has a considerable potential for the removal of heavy metal cationic species from aqueous solution and wastewater.