Open AccessExperimental evidence for a kinetic and electrochemical memory in enzyme membranes.
Author(s) -
Daniel Thomas,
JeanNoël Barbotin,
Alain David,
JeanFrançois Hervagault,
JeanLouis Romette
Publication year - 1977
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.74.12.5314
Subject(s) - membrane , diffusion , substrate (aquarium) , chemistry , hysteresis , electrochemistry , coupling (piping) , urease , chemical physics , enzyme , electrode , biophysics , materials science , chemical engineering , thermodynamics , biochemistry , biology , ecology , physics , quantum mechanics , engineering , metallurgy
The existence of hysteresis phenomena in artificial enzyme membranes due to the coupling of simple kinetic enzyme properties with diffusion transport processes is reported. The intramembrane pH of a urease coating on the surface of a glass pH electrode exhibits a hysteresis loop when the pH of the bulk solution varies cyclically. The steady-state potential of a urease membrane, as a function of the substrate concentration in the bulk solution, also exhibits a memory effect. The influence of the membrane's history on its overall behavior is visualized by electron microscopy. We interpret the results in terms of a coupling between the enzyme reactions and diffusion processes, without taking into account molecular effects.