Axially Unsymmetrical Osmium(II)-Porphyrins with Sulfur and Nitrogen Donors as Models for Cytochrome c Models

✍ Scribed by Prof. Dr. Johann Walter Buchler; Dr. Wolfgang Kokisch

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 326 KB
• Volume: 20
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.198104031

✦ Synopsis

100 mV/SCE, 2 h), in conjunction with the concentration decrease of NADH determined photometrically at 340 nm, show that a two electron transfer occurs with both the modified and unmodified electrodes. No deactivation of the electrodes by fouling was observed in the treated, at 100 mV/ SCE, and untreated electrodes, at 300 mV/SCE, after a 2 h investigation. However, fouling occurred with the unmodified electrode at a potential of 100 mV/SCE. Unspecific responses can be eliminated using a differential circuit of an enzyme-chloranil electrode versus a chloranil electrode.

The chloranil electrode can also be used with a covering dialysis membrane. However, in order to limit the decrease in sensitivity resulting, the membrane and electrolyte films must be as thin as possible.

The extraordinary activity of chloranil with respect to oxidation of NADH is probably due to formation of a chargetransfer complex. In contrast benzoquinone, whose redox potential is only 30 mV lower, is catalytically inactive. The systematic search for other catalysts for NADH-oxidation, which can be irreversibly adsorbed on carbon electrodes, has led to several heterocyclic compounds151.