Activity analysis of immobilized tyrosinase in the presence of different inhibitors

Narlı, Işıl
Immobilization of tyrosinase enzyme was performed in the matrices obtained via copolymerization of terephthalic acid bis-(2-thiophen-3-yl ethyl) ester (TATE) with pyrrole. During electrochemical polymerization of pyrrole, enzyme molecules were entrapped in the copolymer matrice. Activity measurements were performed by using Besthorn̕s Hydrazone method which includes spectrophotometric analysis of quinones produced by the enzyme. Enzyme electrodes were characterized in terms of maximum reaction rate (Vmax) and Michaelis-Menten constant (Km). In addition to kinetic parameters, stability of enzyme electrodes towards environmental conditions such as pH and temperature was investigated. Usage stability and shelf-life analysis were also examined. Wines, especially red wines, contain numerous biologically active compounds, the most important of which are polyphenols, whose nutritional importance is attributed to their antioxidant power. The amounts of phenolic compounds in different red wines were analyzed by using obtained enzyme electrodes. The phenolic compound determination using free enzyme cannot reflect the actual values since there are also naturally found inhibitors in red wines. Benzoic acid, cinnamic acid and sorbic acid were utilized to understand the behavior of immobilized tyrosinase in the conducting polymer matrices toward inhibition.


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Kıralp, Senem; Kıralp, Senem; Department of Chemistry (2004)
A new thiophene derivative containing menthyl group (MM) was synthesized and polymerized via chemical and electrochemical methods. Polymers obtained and MM itself were used to synthesize copolymers with pyrrole under conditions of constant potential electrolysis. Cyclic Voltammetry, thermal analysis and scanning electron microscopy analyses were performed for the characterization of samples. Immobilization of invertase and polyphenol oxidase enzymes was performed in the matrices obtained via copolymerizatio...
Immobilization of tyrosinase in polysiloxane/polypyrrole copolymer matrices
Arslan, Ahu; Toppare, Levent Kamil; Department of Chemistry (2006)
Immobilization of tyrosinase in conducting copolymer matrices of pyrrole functionalized polydimethylsiloxane/polypyrrole (PDMS/PPy) were achieved by electrochemical polymerization. The polysiloxane/polypyrrole/tyrosinase electrode was constructed by the entrapment of enzyme in conducting matrices during electrochemical copolymerization. Maximum reaction rate (Vmax) and Michaelis-Menten constant (Km) were investigated for immobilized enzyme. Enzyme electrodes were prepared in two different electrolyte/solven...
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Cihaner, Atilla; Önal, Ahmet Muhtar; Department of Chemistry (2004)
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Erdem, Yelda; Tinçer, Teoman; Department of Polymer Science and Technology (2005)
This theses covers the preparation and the characterization of a rigid hydrogel from N-Vinyl pyrrolidone-methacrylic acid (VP-MAA) monomers and polyethyleneoxide (PEO) polymer. Hydrogels are hydrophillic natured three dimensional networks which can swell in the presence of water. The VP-MAA-PEO hydrogel was obtained by template polymerization which can be defined as a method of polymer synthesis in which specific interactions consists of the preparation of a polymer (daughter polymer) in the presence of a m...
Characterization of conducting polymers of ester linkage containing thiophene derivatives via mass spectroscopy
Aslan, Evren; Toppare, Levent Kamil; Department of Chemistry (2004)
In order to investigate the thermal and structural characteristics of terepthalic acid bis-(2-thiophen-3-yl-ethyl)ester (TATE), decanedioic acid bis-(2-thiophen-3-yl- ethyl) ester (DATE) and octanoic acid 2-thiophen-3-yl-ethyl ester (OTE), their corresponding homopolymers, copolymers with thiophene and polythiophene, pyrolysis mass spectrometry technique was utilized. The results were discussed in detail considering the effects of spacer group in between ester linkages. Thermal Gravimetry Analysis was used ...
Citation Formats
I. Narlı, “Activity analysis of immobilized tyrosinase in the presence of different inhibitors,” M.S. - Master of Science, Middle East Technical University, 2006.