Sulfhydryl oxidase modified composite electrode for the detection of reduced thiolic compounds

Thiol (SH) groups play a remarkable role in the cell with their redox state affecting the activity and structure of many enzymes, receptors and transcription factors. In the present work, carbon paste electrodes modified with sulfhydryl oxidase (SOX) were prepared. The proposed biosensor was based on the monitoring of the produced peroxide concentration that correlates with the concentration of reduced thiols during the enzymatic reaction. As well as analytical characteristics, optimization in terms of amount of enzyme, pH and temperature were carried out. After that, thiolic compounds (reduced/oxidized glutathione, cysteine, homocysteine, N-acetylcysteine, dl-dithiotreitol) were separated by HPLC and the performance of the sulfhydril oxidase SOX biosensor as a post-column electrochemical detector was investigated for the analysis of these compounds. All data were given as a comparison of two systems; biosensor and diode array detector (DAD).