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51.
Seda Savranoglu Kulabas Ferah Comert Onder Yakup Berkay Yılmaz Adem Ozleyen Kader Sahin 《Journal of biomolecular structure & dynamics》2020,38(15):4655-4668
Communicated by Ramaswamy H. Sarma 相似文献
52.
Gulay Bayramoglu Begum AltintasMeltem Yilmaz M. Yakup Arica 《Bioresource technology》2011,102(2):475-482
Chloroperoxidase (CPO) was covalently immobilized on poly(hydroxypropyl methacrylate-co-polyethyleneglycole-methacrylate) membranes, which were characterized, by swelling test, FT-IR spectroscopy, scanning electron microscopy, and contact angle measurement. The Km and Vmax values for free and immobilized CPO were found to be 34.6 and 47.2 μM, and 287.5 and 245.2 U/mg protein, respectively. The optimum pH for both the free and immobilized enzyme was observed at 3.0. The immobilized enzyme showed wide pH and temperature profiles. Most importantly, the increased thermal, storage and operational stability of immobilized CPO should depend on the creation of a comfortable strong hydrophilic microenvironment on the designed support to the host enzyme molecule. 相似文献
53.
Bayramoglu G Karagoz B Altintas B Arica MY Bicak N 《Bioprocess and biosystems engineering》2011,34(6):735-746
Fibrous poly(styrene-b-glycidylmethacrylate) brushes were grafted on poly(styrene–divinylbenzene) (P(S–DVB)) beads using surface-initiated atom
transfer radical polymerization. Tetraethyldiethylenetriamine (TEDETA) ligand was incorporated on P(GMA) block. The ligand
attached beads were used for reversible immobilization of lipase. The influences of pH, ionic strength, and initial lipase
concentration on the immobilization capacities of the beads have been investigated. Lipase adsorption capacity of the beads
was about 78.1 mg/g beads at pH 6.0. The K
m value for immobilized lipase was about 2.1-fold higher than that of free enzyme. The thermal, and storage stability of the
immobilized lipase also was increased compared to the native lipase. It was observed that the same support enzyme could be
repeatedly used for immobilization of lipase after regeneration without significant loss in adsorption capacity or enzyme
activity. A lipase from Mucor miehei immobilized on styrene–divinylbenzene copolymer was used to catalyze the direct esterification of butyl alcohol and butyric
acid. 相似文献
54.
Tavaré R Sagoo P Varama G Tanriver Y Warely A Diebold SS Southworth R Schaeffter T Lechler RI Razavi R Lombardi G Mullen GE 《PloS one》2011,6(5):e19662
Dendritic cells (DCs) generated in vitro to present tumour antigens have been injected in cancer patients to boost in vivo anti-tumour immune responses. This approach to cancer immunotherapy has had limited success. For anti-tumour therapy, delivery and subsequent migration of DCs to lymph nodes leading to effective stimulation of effector T cells is thought to be essential. The ability to non-invasively monitor the fate of adoptively transferred DCs in vivo using magnetic resonance imaging (MRI) is an important clinical tool to correlate their in vivo behavior with response to treatment. Previous reports of superparamagnetic iron oxides (SPIOs) labelling of different cell types, including DCs, have indicated varying detrimental effects on cell viability, migration, differentiation and immune function. Here we describe an optimised labelling procedure using a short incubation time and low concentration of clinically used SPIO Endorem to successfully track murine DC migration in vivo using MRI in a mouse tumour model. First, intracellular labelling of bone marrow derived DCs was monitored in vitro using electron microscopy and MRI relaxometry. Second, the in vitro characterisation of SPIO labelled DCs demonstrated that viability, phenotype and functions were comparable to unlabelled DCs. Third, ex vivo SPIO labelled DCs, when injected subcutaneously, allowed for the longitudinal monitoring by MR imaging of their migration in vivo. Fourth, the SPIO DCs induced the proliferation of adoptively transferred CD4(+) T cells but, most importantly, they primed cytotoxic CD8(+) T cell responses to protect against a B16-Ova tumour challenge. Finally, using anatomical information from the MR images, the immigration of DCs was confirmed by the increase in lymph node size post-DC injection. These results demonstrate that the SPIO labelling protocol developed in this study is not detrimental for DC function in vitro and in vivo has potential clinical application in monitoring therapeutic DCs in patients with cancer. 相似文献
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56.
Yakup Kolcuoğlu 《Process Biochemistry》2012,47(12):2449-2454
Polyphenol oxidases (PPO) are very important enzymes group in many industrial applications, especially in food, medicine and cosmetics. PPO from Macrolepiota gracilenta, a wild edible mushroom, was purified using a Sepharose 4B-l-tyrosine-p-amino benzoic acid affinity column and characterized in terms of mono- and diphenolase activity. The highest activities for pure enzyme were observed in the presence of PHPPA and DHPPA for monophenolase and diphenolase, respectively. The enzyme showed pH optimum values at 7.0 and 5.0, respectively, for monophenolase and diphenolase activities. Km values calculated as 0.8 mM for monophenolase and 1 mM for diphenolase activity at the presence of PHPPA and DHPPA as substrate, respectively. Vmax values were calculated as 2000 U/mg protein for both activity. Monophenolase and diphenolase activities were conserved approximately 40% and 60%, respectively, in their optimum pH at 4 °C after 5 day incubation. The activities were inhibited most effectively by thiourea. The data obtained from this study showed that this enzyme could be useful for some industrial purposes. 相似文献
57.
Sevinc Tuncagil Senem Kiralp Kayahan Gulay Bayramoglu M. Yakup Arica Levent Toppare 《Journal of Molecular Catalysis .B, Enzymatic》2009,58(1-4):187-193
Magnetic beads were prepared via suspension polymerization of glycidyl methacrylate (GMA) and methyl methacrylate (MMA) in the presence of ferric ions. Following polymerization, thermal co-precipitation of the Fe(III) ions in the beads with Fe(II) ions under alkaline condition resulted in encapsulation of Fe3O4 nano-crystals within the polymer matrix. The magnetic beads were activated with glutaraldehyde, and tyrosinase enzyme was covalently immobilized on the support via reaction of amino groups under mild conditions. The immobilized enzyme was used for the synthesis of l-Dopa (1-3,4-dihydroxy phenylalanine) which is a precursor of dopamine. The immobilized enzyme was characterized by temperature, pH, operational and storage stability experiments. Kinetic parameters, maximum velocity of the enzyme (Vmax) and Michaelis–Menten constant (Km) values were determined as 1.05 U/mg protein and 1.0 mM for 50–75 μm and 2.00 U/mg protein and 4.0 mM for 75–150 μm beads fractions, respectively. Efficiency factor and catalytic efficiency were found to be 1.39 and 0.91 for 75–150 μm beads and 0.73 and 0.75 for 50–75 μm beads fractions, respectively. The catalytic efficiency of the soluble tyrosinase was 0.37. The amounts of immobilized protein were on the 50–75 μm and 75–150 μm fractions were 2.7 and 2.8 mg protein/g magnetic beads, respectively. 相似文献
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Alicigüzel Y Aktaş S Bozan H Aslan M 《Journal of enzyme inhibition and medicinal chemistry》2005,20(3):293-296
Intravenous nitroglycerin (GTN) has been used as an anti-ischemic agent for the therapy of unstable and post-infarction angina. Nitric oxide (NO) and S-nitrosothiols constitute the biologically active species formed via nitroglycerin bioactivation. Increased levels of reactive oxygen species can diminish the therapeutic action of organic nitrates by scavenging donated NO and oxidizing tissue thiols important in nitrate biotransformation. Studies reported here show that the red cell activity of antioxidant enzymes, catalase and glutathione peroxidase, are significantly decreased after intravenous nitroglycerin treatment. Catalase activity (739.6 +/- 92.3 k/gHb) decreased to 440.1 +/- 111.9 and 459.8 +/- 130.7 k/gHb after 1 and 24 hr GTN infusion, respectively. Similarly, glutathione peroxidase activity (5.8 +/- 1.8 U/gHb) decreased to 3.2 +/- 1.7 and 3.8 +/- 1.1 U/g Hb after 1 and 24 hr GTN infusion, respectively. The reported decrease in antioxidant enzyme activities can lead to an oxidant milieu and contribute to the generation of nitrate tolerance. 相似文献