Electron Transfer and Stability of a Quinohaemoprotein Alcohol Dehydrogenase Electrode

Abstract

Quinohaemoprotein alcohol dehydrogenase from Comamonas testosteroni (QH‐EDH) was immobilised in a redox polymer network of a polyvinylpyridine, partially N‐complexed with osmiumbis(bipyridine)chloride. Substrate‐dependent electron transfer occurred, indicating that the enzyme was active and that effective electron transport was achieved. It was shown that the enzyme molecular weight is of importance with respect to the enzyme electrode stability. Long term stability and current density of the QH‐EDH electrodes were highest when the enzyme was immobilised at pH 10·0 and 4°C, followed by an additional cross‐linking step with glutaraldehyde (1%) at pH 7·0. With such an electrode current densities of 40 μA cm−2 were obtained for several primary alcohols. The affinity of the immobilised enzyme for these substrates (Km(app) values) was similar to that of the enzyme in solution. The half‐life time of the electrodes was between 50 h and 200 h depending on the time the enzyme was in contact with the substrate. When the immobilised enzyme electrode was operated at temperatures above 37°C the stability decreased. © 1997 SCI.

Carbon electrodes for direct electron transfer type laccase cathodes investigated by current density–cathode potential behavior

“…In the absence of laccase all investigated materials exhibit an open circuit potential between 0.2 V and 0.4 V vs. SCE due to the inherent catalytic activity of carbon towards oxygen reduction (Kerzenmacher et al, 2008;Kim et al, 2004;Stigter et al, 1997;Yeager, 1984). Addition of laccase to the testing solution greatly…”

Amperometric detection of methanol with a methanol dehydrogenase modified electrode sensor

“…A third class of alcohol dehydrogenases, pyrroloquinoline quinone (PQQ) dependent alcohol dehydrogenases (EC1.1.99.8), has also been employed in biosensor designs for ethanol [18][19][20][21][22][23][24][25][26][27][28][29][30]. In contrast, methanol dehydrogenase (MDH) from which PQQ was first purified [31] has been rarely used in sensing applications [27,32].…”

Comamonas

“…The encoding gene (qhedh) has been cloned, sequenced, and expressed in E. coli (Stoorvogel et al, 1996). The enzyme has been investigated for use in the production of (S)-solketal (2,2-dimethyl-1,3-dioxolane-4-methanol) by enantio-selective oxidation of racemic solketal (Geerlof et al, 1994a) and has been applied in electrodes through immobilization in a redox polymer network (Stigter et al, 1997). Quinoline 2-oxido-reductase and 2-oxo-1,2-dihydroquinoline 5,6-dioxygenase, the enzymes involved in the first two steps of the degradation of quinoline and 3-methyl quinoline, have been isolated from Comamonas testosteroni strain 63 and their structure and cofactors studied.…”