کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1274603 972621 2011 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Direct electron transfer enhancement of covalently bound tyrosinase to glassy carbon via Woodward's reagent K
موضوعات مرتبط
مهندسی و علوم پایه شیمی الکتروشیمی
پیش نمایش صفحه اول مقاله
Direct electron transfer enhancement of covalently bound tyrosinase to glassy carbon via Woodward's reagent K
چکیده انگلیسی

This work describes the reaction mechanism for chemical modification of tyrosinase by Woodward's Reagent K and its covalent attachment to a glassy carbon electrode. The spectrophotometric studies revealed that the modification does not cause a significant structural change to tyrosinase. The direct electrochemistry of modified enzyme was achieved after immobilization on an oxidatively activated glassy carbon electrode. The enzyme film exhibited a pair of well-defined quasi-revesible voltammetric peaks corresponding to the Cu (II)/Cu (I) redox couple located in the active site of tyrosinase. The formal potential of immobilized enzyme was measured to be 90 mV (vs. Ag/AgCl) in phosphate buffer solution at pH 7.0. The charge-transfer coefficient and apparent heterogeneous electron transfer rate constant were estimated to be 0.5 and 0.9 ± 0.06 s− 1, respectively. Finally, the electrochemical behavior of the immobilized enzyme in the presence of caffeic acid and L-3,4-dihydroxyphenylalanine as substrates was investigated. The amperometric study of biosensor toward L-3,4-dihydroxyphenylalanine resulted a linear response in the concentration range from 1.66 × 10− 6 to 8.5 × 10− 5 M with detection limit of 9.0 × 10−5 M and sensitivity of 135 mA μM− 1 cm− 2.

Research highlights
► The reaction mechanism for chemical modification of tyrosinase by Woodward's reagent K and its covalent attachment to glassy carbon electrode was presented.
► The modification did not cause distinguished changes in tyrosinase structure and activity.
► Using this modification the direct electrochemistry of enzyme was achieved.
► Due to the covalently attachment of enzyme to the electrode surface, a satisfactory storage and operational stability was obtained for the immobilized enzyme.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Bioelectrochemistry - Volume 82, Issue 1, August 2011, Pages 1–9
نویسندگان
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