Tryptophan repressor-binding proteins from Escherichia coli and Archaeoglobus fulgidus as new catalysts for 1,4-dihydronicotinamide adenine dinucleotide-dependent amperometric biosensors and biofuel cells.
The tryptophan (W) repressor-binding proteins (WrbA) from Escherichia coli (EcWrbA) and Archaeoglobus fulgidus (AfWrbA) were investigated for possible use in 1,4-dihydronicotinamide adenine dinucleotide (NADH) dependent amperometric biosensors and biofuel cells. EcWrbA and AfWrbA are oligomeric flavoproteins binding one flavin mononucleotide (FMN) per monomer and belonging to a new family of NAD(P)H:quinone oxidoreductases (NQOs). The enzymes were covalently linked to a low potential Os redox polymer onto graphite in the presence of single-walled carbon nanotube (SWCNT) preparations of varying average lengths. The performance of the enzyme modified electrodes for NADH oxidation was strongly depending on the average length of the applied SWCNTs. By blending the Os redox polymer with SWCNTs, the electrocatalytic current could be increased up to a factor of 5. Results obtained for AfWrbA modified electrodes were better than those for EcWrbA. For NADH detection, a linear range between 5 microM and 1 mM, a lower limit of detection of 3 microM, and a sensitivity of 56.5 nA microM(-1) cm(-2) could be reached. Additionally spectroelectrochemical measurements were carried out in order to determine the midpoint potentials of the enzymes (-115 mV vs NHE for EcWrbA and -100 mV vs NHE for AfWrbA pH 7.0). Furthermore, an AfWrbA modified electrode was used as an anode in combination with a Pt black cathode as a biofuel cell prototype.
Zafar
Muhammad Nadeem
MN
Department of Analytical Chemistry/Biochemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
Tasca
Federico
F
Gorton
Lo
L
Patridge
Eric V
EV
Ferry
James G
JG
Nöll
Gilbert
G
D019843:Archaeal Proteins / Q000378:metabolism*; D019611:Archaeoglobus fulgidus / Q000201:enzymology*; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D002384:Catalysis; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004566:Electrodes; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D009243:NAD / Q000032:analysis*; D037742:Nanotubes, Carbon / Q000737:chemistry; D010084:Oxidation-Reduction; D010984:Platinum / Q000737:chemistry; D012097:Repressor Proteins / Q000378:metabolism*
D019843:Archaeal Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D037742:Nanotubes, Carbon; D012097:Repressor Proteins; C081759:WrbA protein, E coli; D009243:NAD; D010984:Platinum