Use of a biosensor consisting of an immobilized NADH oxidase column and a hydrogen peroxide electrode for the determination of serum lactate dehydrogenase activity
✍ Scribed by Masayoshi Tabata; Fumiyo Koushima; Masayuki Totani
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 580 KB
- Volume
- 298
- Category
- Article
- ISSN
- 0003-2670
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✦ Synopsis
A sensitive flow system for electrochemical determination of the reduced coenzyme NADH was developed using immobilized NADH oxidase from Buciflus lichenifomis.
The immobilized enzyme was packed into a 20 mm x 2 mm I.D. mini-column, and the sample volume used was only 5 ~1 per assay, with an assay time of approximately 20 s and a detection limit of 100 pmol NADH. The flow system using a biosensor consisting of an immobilized NADH oxidase column and a hydrogen peroxide electrode was applied to the determination of lactate dehydrogenase (LDH) activity in human serum, which was obtained by measuring the NADH produced in the LDH reaction for 3 min at 37°C. The use of an immobilized NADH oxidase column avoided interference by NADH peroxidase in the NADH oxidase preparation. The present method gave a linear response up to 3120 I.U. 1-l LDH with satisfactory reproducibility and accuracy. The serum LDH activity correlated satisfactorily with that obtained by a well-established spectrophotometric method. The immobilized enzyme reactor unit showed good operational stability over a 2-month period, during which it was repeatedly used for over 1600 analyses.