Oxidation of NADH produced by a lactate dehydrogenase immobilised on poly(aniline)-poly(anion) composite films

Simon, Evelyne, Halliwell, Catherine M., Toh, Chee Seng, Cass, Anthony E.G. and Bartlett, Philip N. (2002) Oxidation of NADH produced by a lactate dehydrogenase immobilised on poly(aniline)-poly(anion) composite films. Journal of Electroanalytical Chemistry, 538-539, 253-259. (doi:10.1016/S0022-0728(02)00833-1).

Abstract

The immobilisation of enzymes is important for applications in bioelectrochemistry such as biosensors or biofuel cells. In this paper we report the immobilisation of lactate dehydrogenase (LDH) on poly(aniline)–poly(acrylate) [PANi–PAA] and poly(aniline)–poly(vinylsulfonate) [PANi–PVS] composite films. Two genetically engineered forms of LDH (E.C.1.1.1.27) from Bacillus stearothermophilus, one with a poly(histidine) tag on the C-Terminus (LDH-CHis) the other with a poly(histidine) tag on the N-terminus (LDH-NHis), together with the wild type enzyme (WT-LDH) were studied. The LDH-CHis and LDH-NHis both have better affinity for the poly(aniline)–poly(anion) composite films than the WT-LDH. The immobilised LDH reduces the coenzyme NAD+ to NADH and oxidises the substrate, -lactate, to pyruvate. The NADH produced is then oxidised at the poly(aniline)–poly(anion) composite films. The effects of buffer concentration, temperature, NAD+ concentration, enzyme immobilisation conditions, film thickness and electrode rotation rate on the catalytic current were all investigated.

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Contributors

Author: Philip N. Bartlett

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