A tryptophan-2-monooxygenase based amperometric biosensor for L- tryptophan determination: Use of a competitive inhibitor as a tool for selectivity increase

A. L. Simonian, E. I. Rainina, P. F. Fitzpatrick, J. R. Wild

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

A new flow-injection amperometric biosensor based on immobilized tryptophan-2-monooxygenase (TMO) has been developed for reagentless L- tryptophan determination. Concentrations of L-tryptophan between 0.1 and 50 mM could be measured with the linear part of the calibration curve between 0.1 and 2 mM. The response time was 30 s and the total analysis time was less than 3 min. The biosensor retained activity for greater than 4 months, when operated daily at 25°C and stored at 8°C. The biosensor was characterized by a relatively high sensitivity to phenylalanine (54% that of L-tryptophan), a modest response to L-methionine (less than 6%) and virtually no response to other amino acids. However, the biosensor selectivity to L-tryptophan could be dramatically increased when indoleacetamide (IA), a competitive inhibitor of TMO, was introduced. In the presence of 10 μM IA, the biosensor response to L-phenylalanine decreased to 7.4% of the unaffected rate for L-tryptophan. In the absence of L- tryptophan and IA the biosensor could be used for L-phenylalanine determination in the concentration range from 1 to 50 mM. The biosensor was successfully used for L-tryptophan determination in nutritional broth.

Original languageEnglish (US)
Pages (from-to)363-371
Number of pages9
JournalBiosensors and Bioelectronics
Volume12
Issue number5
DOIs
StatePublished - Aug 5 1997

Keywords

  • Biosensor
  • Indoleacetamide
  • L- phenylalanine
  • L-tryptophan
  • L-tryptophan-2-monooxygenase

ASJC Scopus subject areas

  • Biotechnology
  • Biophysics
  • Biomedical Engineering
  • Electrochemistry

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