Enzyme-based catechol sensor based on the cyclic reaction between catechol and 1,2-benzoquinone, using l-ascorbate and tyrosinase

✍ Scribed by Shunichi Uchiyama; Yasushi Hasebe; Hiroya Shimizu; Hideki Ishihara

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 457 KB
• Volume: 276
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(93)80402-7

✦ Synopsis

A cyclic reaction between catechol and 1,2-benzoquinone takes place by combining the tyrosinase reaction and the chemical reduction of 1,2benzoquinone to catechol by L-ascorbic acid. Catechol is oxidized by the dissolved oxygen catalysed by the enzyme and its consumption is not compensated for by the chemical regeneration of catechol from 1,2-benzoquinone. The dissolved oxygen thus continues to decrease during the cyclic reaction and consequently the decrease in the reduction current of oxygen is amplified. The amplification factor of 1 X low6 M catechol at 0.01 M L-ascorbate and pH 7.0 was found to be 300 when enzyme activity was 20 U ml-' and the reaction time was 10 min. The calibration graph for catechol obtained with a potato tissue membrane electrode was moved in parallel to a lower concentration range and the detection limit was found to be 5 X lo-' M (amplification factor 4&l) when buffer solution of pH 7.0 containing 0.01 M L-ascorbic acid was used.