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Photoelectrochemical bioanalysis of guanosine monophosphate via the use of coupled enzymatic reactions at a CdS/ZnS quantum dot electrode.

MPS-Authors
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Khan,  N.
Research Group of Enzyme Biochemistry, MPI for biophysical chemistry, Max Planck Society;

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Konrad,  M.
Research Group of Enzyme Biochemistry, MPI for biophysical chemistry, Max Planck Society;

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Citation

Sabir, N., Khan, N., Völkner, J., Widdascheck, F., del Pino, P., Witte, G., et al. (2015). Photoelectrochemical bioanalysis of guanosine monophosphate via the use of coupled enzymatic reactions at a CdS/ZnS quantum dot electrode. Small, 11(43), 5844-5850. doi:10.1002/smll.201501883.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0028-465F-E
Abstract
A photo-electrochemical sensor for the specific detection of guanosine monophosphate (GMP) is demonstrated, based on three enzymes combined in a coupled reaction assay. The first reaction involves the adenosine triphosphate (ATP)-dependent conversion of GMP to guanosine diphosphate (GDP) by guanylate kinase, which warrants substrate specificity. The reaction products ADP and GDPare co-substrates for the enzymatic conversion of phosphoenolpyruvate to pyruvate in a second reaction mediated by pyruvate kinase. Pyruvate in turn is the co-substrate for lactate dehydrogenase that generates lactate via oxidation of nicotinamide adenine dinucleotide (reduced form) NADH to NAD+. This third enzymatic reaction is electrochemically detected. For this purpose a CdS/ZnS quantum dot (QD) electrode is illuminated and the photocurrent response under fixed potential conditions is evaluated. The sequential enzyme reactions are first evaluated in solution. Subsequently, a sensor for GMP is constructed using polyelectrolytes for enzyme immobilization.