Chem. Anal. (Warsaw), 52, 945 (2007) Keywords: Cellobiose dehydrogenase; Myriococcum thermophilum; Thiol modified gold electrode; Direct electron transfer; Bioelectrocatalysis Investigation of Electron Transfer Between Cellobiose Dehydrogenase From Myriococcum Thermophilum and Gold Electrodes by Vasile Coman 1 *, Wolfgang Harreither 2 , Roland Ludwig 2,3 , Dietmar Haltrich 2 and Lo Gorton 1 * 1 Department of Analytical Chemistry, Lund University, P. O. Box 124, SE-221 00 Lund, Sweden 2 Division of Food Biotechnology, Department of Food Sciences and Technology, BOKU-University of Natural Resources and Applied Life Sciences Vienna, Muthgasse 18, A-1190 Wien, Austria 3 Research Centre Applied Biocatalysis, Petersgasse 18, A-8010 Graz, Austria Cellobiose dehydrogenase (CDH) is a monomeric protein consisting of two subdomains: a larger flavin-associated domain (DH cdh ) and a smaller heme-binding domain (CYT cdh ), connected via a protease cleavable linker region. In this study, the inter-domain electron transfer, using the CDH from the ascomycete fungus Myriococcum thermophilum and thiol (SAM) modified gold electrodes, was investigated with cyclic voltammetry and UVVIS spectroelectrochemistry. The effect of the SAM and pH on the formal potential of the heme domain of CDH and on the current generated by the electrocatalytic oxidation of cellobiose and lactose was evaluated with voltammetric techniques. The oxidation-reduction midpoint potentials of the DH cdh , CYT cdh , and whole CDH unit were estimated at different pH values using a long-optical-pathway thin capillary-type spectroelectrochemical cell. * Corresponding author. E-mail:Vasile.Coman@analykem.lu.se, Lo.Gorton@analykem.lu.se, Fax: +46 46 222 4544 Dehydrogenaza celobiozowa (CDH) jest bia‡kiem monomerycznym z‡o¿onym z dwch czŒci (domen)  wiŒkszej po‡„czonej z flawin„ (DH cdh ) i mniejszej po‡„czonej z hemem (CYT cdh ). Obie domeny s„ po‡„czone rozszczepialnym ‡„cznikiem z proteazy. W pracy przed- stawiono badania przeniesienia elektronu miŒdzy domenami CDH pochodz„cej z grzyba Myriococcum thermofilum. Do badaæ u¿yto z‡otych elektrod modyfikowanych tiolem (samo- uporz„dkowanie, SAM), cyklicznej woltamperometrii oraz UVVIS spektroelektrochemii.