TY  - JOUR
A1  - Mitrova, Biljana
A1  - Tadjoung Waffo, Armel Franklin
A1  - Kaufmann, Paul
A1  - Iobbi-Nivol, Chantal
A1  - Leimkühler, Silke
A1  - Wollenberger, Ulla
T1  - Trimethylamine N-Oxide Electrochemical Biosensor with a Chimeric Enzyme
JF  - ChemElectroChem
N2  - For the first time, an enzyme-based electrochemical biosensor system for determination of trimethylamine N-oxide (TMAO) is described. It employs an active chimeric variant of TorA in combination with an enzymatically deoxygenating system and a low-potential mediator for effective regeneration of the enzyme and cathodic current generation. TMAO reductase (TorA) is a molybdoenzyme found in marine and most enterobacteria that specifically catalyzes the reduction of TMAO to trimethylamine (TMA). The chimeric TorA, named TorA-FDH, corresponds to the apoform of TorA from Escherichia coli reconstituted with the molybdenum cofactor from formate dehydrogenase (FDH). Each enzyme, TorA and TorA-FDH, was immobilized on the surface of a carbon electrode and protected with a dialysis membrane. The biosensor operates at an applied potential of -0.8V [vs. Ag/AgCl (1M KCl)] under ambient air conditions thanks to an additional enzymatic O-2-scavenger system. A comparison between the two enzymatic sensors revealed a much higher sensitivity for the biosensor with immobilized TorA-FDH. This biosensor exhibits a sensitivity of 14.16nA/M TMAO in a useful measuring range of 2-110M with a detection limit of LOD=2.96nM (S/N=3), and was similar for TMAO in buffer and in spiked serum samples. With a response time of 16 +/- 2 s, the biosensor is stable over prolonged daily measurements (n=20). This electrochemical biosensor provides suitable applications in detecting TMAO levels in human serum.
KW  - trimethylamine N-oxide (TMAO)
KW  - TMAO reductase
KW  - chimeric enzyme
KW  - molybdoenzyme
KW  - electrochemical biosensor
Y1  - 2018
U6  - https://doi.org/10.1002/celc.201801422
SN  - 2196-0216
VL  - 6
IS  - 6
SP  - 1732
EP  - 1737
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Tiedemann, Kim
A1  - Iobbi-Nivol, Chantal
A1  - Leimkühler, Silke
T1  - The Role of the Nucleotides in the Insertion of the bis-Molybdopterin Guanine Dinucleotide Cofactor into apo-Molybdoenzymes
JF  - Molecules
N2  - The role of the GMP nucleotides of the bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor of the DMSO reductase family has long been a subject of discussion. The recent characterization of the bis-molybdopterin (bis-Mo-MPT) cofactor present in the E. coli YdhV protein, which differs from bis-MGD solely by the absence of the nucleotides, now enables studying the role of the nucleotides of bis-MGD and bis-MPT cofactors in Moco insertion and the activity of molybdoenzymes in direct comparison. Using the well-known E. coli TMAO reductase TorA as a model enzyme for cofactor insertion, we were able to show that the GMP nucleotides of bis-MGD are crucial for the insertion of the bis-MGD cofactor into apo-TorA.
KW  - bis-MGD
KW  - chaperone
KW  - molybdenum cofactor
KW  - TMAO reductase
Y1  - 2022
U6  - https://doi.org/10.3390/molecules27092993
SN  - 1420-3049
VL  - 27
SP  - 1
EP  - 15
PB  - MDPI
CY  - Basel, Schweiz
ET  - 9
ER  -