A bienzyme electrode for tyrosine-containing peptides determination |
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Authors: | Arkadi V. Eremenko Alexander Makower Christian G. Bauer Ilya N. Kurochkin Frieder W. Scheller |
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Affiliation: | 1. Department of Biosensors, Research Center for Molecular Diagnostics & Therapy, Simpheropolsky blvd. 8, 113149 Moscow, Russia;2. Department of Analytical Biochemistry, Institute of Biochemistry and Molecular Physiology, Potsdam University, Robert-Roessle-Str. 10, D-13122 Berlin-Buch, Germany |
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Abstract: | A bienzyme electrode for monitoring biologically important peptides containing tyrosine has been established on the basis of mushroom tyrosinase and quinoprotein glucose dehydrogenase (GDH). Tyrosine residues bound in the peptide chain are oxidized by tyrosinase resulting in consumption of oxygen. Subsequently, the dopaquinone residues are reduced in the GDH catalysed reaction which is driven by an excess of glucose. This reaction cycle leads to a considerable increase of sensitivity. Both enzymes were entraped in poly(vinyl)alcohol matrix and placed on the surface of a Clark-type oxygen electrode (the working platinum electrode was potentiostated at −600 mV) (vs. Ag/AgCl reference electrode) between a polypropylene and cellulose membrane. The bienzyme-modified Clark-type oxygen electrode has a lower detection limit of 0.2 μM for the opioid peptides Tyr-D-Ser-Gly-Phe-Leu-Thr, Leu-enkephalin, Tyr-D-Ala-Gly-Phe-D-Leu and morphiceptin. The dependence of response of the electrode on the length of peptide chain and position of tyrosine residue is discussed. The new electrode has been applied to the quality control of tyrosine containing peptides from pharmaceutical formulations and from peptide synthesis. |
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Keywords: | Bienzyme electrode Tyrosinase Glucose dehydrogenase Tyrosine containing peptides |
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