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Electrode adsorption method for determination of enzymatic activity

  • H. Arwin
  • I. Lundström
  • A. Palmqvist
Article

Abstract

The paper describes an electrical method for the determination of enzymatic activity. It is based on the fact that certain peptides, which are hydrolysed by enzymes, adsorb on a metal electrode in such a way that the double-layer capacitance of the electrode is changed. The two parts of the hydrolysed peptide do not have this property. The capacitance change depends on the concentration of the peptide and can be used to measure it. We describe more specifically the use of the tripeptide Bz-Phe-Val-Arg-pNA, which is a substrate for enzymes like thrombin and trypsin. Some different ways to use the electrode method are described. The determination of antithrombin activity in plasma and whole blood is taken as a practical example. The necessary instrumentation is briefly described with special attention to an automated equipment, which controls the experimental conditions and reduces errors due to the operator. Experimental results from studies of the frequency dispersion of the electrode impedance are presented. A model for the influence of the adsorbed peptides on the electrical properties of the electrode is derived. Finally, some general remarks are made about the applicability of the electrode adsorption method.

Keywords

Ac-admittance Adsorption Capacitance Electrodes Enzyme activity Platinum Thrombin Tripeptide 

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Copyright information

© IFMBE 1982

Authors and Affiliations

  • H. Arwin
    • 1
  • I. Lundström
    • 1
  • A. Palmqvist
    • 1
  1. 1.Laboraatory of Applied Physics, Department of Physics and Measurement TechnologyLinköping UniversityLinköpingSweden

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