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    Antibody purification with protein A attached supermacroporous poly(hydroxyethyl methacrylate) cryogel
    (Elsevier, 2009) Alkan, Hueseyin; Bereli, Nilay; Baysal, Zuebeyde; Denizli, Adil
    Immunoglobulin G (IgG) Purification from human plasma with protein A attached supermacroporous poly(hydroxyethyl methacrylate) [PHEMA] cryogel has been studied. PHEMA cryogel was prepared by bulk polymerization which proceeds in aqueous solution of monomer frozen inside a plastic syringe (cryo-polymerization). After thawing, the PHEMA cryogel contains a Continuous matrix having interconnected pores of 10-200 mu m size. Protein was covalently attached onto the PHEMA cryogel via cyanogen bromide (CNBr) activation. The maximum IgG adsorption oil the PHEMA/protein A cryogel Was found to be 83.2 mg/g at pH 7.4 from aqueous Solutions. The non-specific IgG adsorption onto the PHEMA cryogel was about 0.38 mg/g. The macropore size of the cryogel makes it possible to process blood cells without blocking the Column. Higher adsorption capacity was observed from human plasma (Lip to 88.1 mg/g). Adsorbed IgG was eluted using 0.1 M glycine-HCl buffer (pH 3.5) with a purity of 85%. PHEMA-protein A cryogel was used for repetitive adsorption/desorption of IgG without noticeable loss in IgG adsorption capacity after 10 cycles. PHEMA-protein A cryogel showed several advantages Such as simpler preparation procedure, good selectivity for IgG Purification from human plasma and good stability throughout repeated adsorption-desorption cycles. (C) 2009 Elsevier B.V. All rights reserved.
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    Öğe
    Cu2+-attached pumice particles embedded composite cryogels for protein purification
    (Taylor & Francis Ltd, 2017) Alkan, Hueseyin; Comert, Seyda Ceylan; Gurbuz, Fatma; Dogru, Mehmet; Odabasi, Mehmet
    In this study, chromatographic performance of Cu2+-attached pumice particles embedded to monolithic cryogels (Cu2+-APPsEMC) for human serum albumin (HSA) was investigated. Monolithic composite cryogels were prepared by means of polymerization of gel-forming precursors at sub-zero temperatures. The chemical composition of pumice and surface of composite cryogels were determined by X-ray fluorescence spectrometer and scanning electron microscopy, respectively. The highest adsorption capacity (549.5 mg/g pumice) of cryogels was achieved at phosphate buffer of pH 8.0 with initial HSA solution of 3 mg/ml. SDS-PAGE analysis was performed for the samples studied on human serum to determine HSA adsorption/desorption performance of cryogel qualitatively.
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    Equilibrium and thermodynamic studies on biosorption of Pb(II) onto Candida albicans biomass
    (Elsevier Science Bv, 2009) Baysal, Zuebeyde; Cinar, Ercan; Bulut, Yasemin; Alkan, Hueseyin; Dogru, Mehmet
    Biosorption of Pb(II) ions from aqueous solutions was studied in a batch system by using Candida albicans. The optimum conditions of biosorption were determined by investigating the initial metal ion concentration, contact time, temperature, biosorbent dose and pH. The extent of metal ion removed increased with increasing contact time, initial metal ion concentration and temperature. Biosorption equilibrium time was observed in 30 min. The Freundlich and Langmuir adsorption models were used for the mathematical description of biosorption equilibrium and isotherm constants were also evaluated. The maximum biosorption capacity of Pb(II) on C. albicans was determined as 828.50 +/- 1.05, 831.26 +/- 1.30 and 833.33 +/- 1.12 mg g(-1), respectively, at different temperatures (25, 35 and 45 degrees C). Biosorption showed pseudo second-order rate kinetics at different initial concentration of Pb(II) and different temperatures. The activation energy of the biosorption (E-a) was estimated as 59.04 kJ mol(-1) from Arrhenius equation. Using the equilibrium constant value obtained at different temperatures, the thermodynamic properties of the biosorption (Delta G degrees, Delta H degrees and Delta S degrees) were also determined. The results showed that biosorption of Pb(II) ions on C. albicans were endothermic and spontaneous. The optimum initial pH for Pb(II) was determined as pH 5.0. FTIR spectral analysis of Pb(II) adsorbed and unadsorbed C. albicans biomass was also discussed. (C) 2008 Elsevier B.V. All rights reserved.
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    Production of extracellular alkaline ?-amylase by solid state fermentation with a newly isolated Bacillus sp.
    (Taylor & Francis Inc, 2008) Baysal, Zuebeyde; Uyar, Fikret; Dogru, Mehmet; Alkan, Hueseyin
    Production of alkaline -amylase employing our laboratory isolate, Bacillus sp., under solid state fermentation, was optimized. The effect of wheat bran and lentil husk was examined. Lentil husk exhibited the highest enzyme production. The appropriate incubation time, inoculum size, moisture level, and buffer solution level were determined. Maximum yields of 216,000 and 172,800 U/g were achieved by employing lentil husk and wheat bran as substrates in 0.1 M carbonate/bicarbonate buffer at pH 10.0 with 30% initial moisture level at 24h. Inoculum size and buffer solution level were found to be 20% and 1:0.5 for two solid substrates.