Autori: Leonard Stoica, Tautgirdas Ruzgas, Roland Ludwig, Dietmar Haltrich, Lo Gorton

Editorial: Allen J. Bard, Richard M. Crooks, and David G. Whitten, ACS Publications, Langmuir (Part of the Electrochemistry special issue), 22, p.10801-1080, 2006.

Rezumat:

This paper presents some functional differences as well as similarities observed when comparing the newly discovered cellobiose dehydrogenase (CDH) from Trametes Villosa (T.V.) with the well-characterized one from Phanerochaete chrysosporium (P.c.). The enzymes were physically adsorbed on spectrographic graphite electrodes placed in an amperometric flow through cell connected to a flow system. In the case of T.V.-CDH-modified graphite electrodes, a high direct electron transfer (DET) current was registered at the polarized electrode in the presence of the enzyme substrate reflecting a very efficient internal electron transfer (IET) process between the reduced FAD-cofactor and the oxidized heme-cofactor. In the case of P.c.-CDH-modified graphite electrodes, the DET process is not as efficient, and the current will greatly increase in the presence of a mediator (mediated electron transfer, MET). As a consequence, when comparing the two types of enzyme-modified electrodes an inverted DET/MET ratio for T.V.-CDH is shown, in comparison with P.c.-CDH. The rates of the catalytic reaction were estimated to be comparable for both enzymes, by measuring the combined DET + MET currents. The inverted DET/MET ratio for T.V.-CDH-modified electrodes might suggest that probably there is a better docking between the two domains of this enzyme and that the linker region of P.c.-CDH might have an active role in modulating the rate of the IET (by changing the interdomain distance), with respect to pH. Based on the new properties of T.V.-CDH emphasized in the present study, an analytical application
of a third-generation biosensor for lactose was recently published.

Cuvinte cheie: direct electron transfer, biosensor, self-substrate inhibition, inter-domains linker

URL: http://pubs.acs.org/journals/langd5/index.html