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Influence of acceptor functionality on charge transfer interactions in mixtures of poly(9-vinylcarbazole) with nitroaromatic compounds

100%

Grigoras A., Barboiu V.

Open Chemistry

2012

vol. 10

issue 2

313-319

Charge transfer interactions in mixtures of poly(9-vinylcarbazole) with three nitro compounds (4,4′dinitrodibenzyl, ethyl 3,5-dinitrobenzoate and 2,2′,4,4′-tetranitrodibenzyl) were examined. GPC shows an increase of apparent polymer weight average molecular weight (MW) in mixtures compared with pure PVK. Electron acceptors show upfield 1H-NMR shifts for all mixtures. The equilibrium association constants (k) calculated from the Benesi-Hildebrand equation are 0.511, 1.371, and 1.868 L mol−1 for PVK blends with DNDB, DNBE and TNDB, respectively. Shifts of (−NO2) stretch vibrations in mixtures support charge transfer complex formation between PVK chains and electron acceptors The ability to accept electrons decreases: TNDB>DNBE>DNDB. [...]

Stabilization of horseradish peroxidase by covalent conjugation with dextran aldehyde against temperature and pH changes

100%

Altikatoglu M., Arioz C., Basaran Y., Kuzu H.

Open Chemistry

2009

vol. 7

issue 3

423-428

Stabilization of Horseradish Peroxidase (HRP; EC 1.11.1.7) against temperature and pH via the formation of the conjugates obtained by multipoint covalent bonding of dextran aldehyde (DA) to the enzyme were studied. Hence, three different molar weighted dextrans (17.5 kD, 75 kD, 188 kD) were covalently bonded to purified enzyme with different molar ratios (nHRP/nDA 20/1, 10/1, 1/1, 1/5, 1/10, 1/15, 1/20). The thermal stabilities of the obtained conjugates were evaluated with the activities determined at different temperatures (25, 30, 35, 40, 50, 60, 70, 80°C) applying 60 minutes incubation time. Conjugates formed were characterized by gel-permeation chromatography (GPC) and fluorescence techniques. The conjugate synthesized using dextran 75 kDa with nHRP/nDA 1/10 molar ratio showed better thermal stability than other conjugates and purified enzyme at pH 7. This conjugate also has wider activity pH range than purified enzyme. In addition, mentioned conjugate at pH 7 had very long storage lifetime compared to purified enzyme at +4°C and room temperature; which is considered a favorable feature for usage in practice. [...]

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2 Open Chemistry

1 2012

1 2009

1 Altikatoglu M.

1 Arioz C.

1 Barboiu V.

1 Basaran Y.

1 Grigoras A.

1 Kuzu H.

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Influence of acceptor functionality on charge transfer interactions in mixtures of poly(9-vinylcarbazole) with nitroaromatic compounds

Stabilization of horseradish peroxidase by covalent conjugation with dextran aldehyde against temperature and pH changes