Role of differential transport in an oscillatory enzyme reaction.
As a result of the bell-shaped pH-rate characteristic of enzymatic processes, feedback may arise in enzyme reactions having non-neutral products. This special type of product activation has been shown to lead to self-sustained pH oscillations in an enzyme-loaded membrane. We investigate the possibility of oscillations in a model of the urea-urease reaction, prompted by the recent experimental discovery of feedback in this reaction. An open system is considered in which acid and urea are transported to a cell containing the enzyme. Using linear stability analysis we determine the range of transport coefficients limit cycles may exist for and show that differential transport is required for oscillations in a class of compartmentalized enzyme processes similar to the urea-urease system. We demonstrate that although the transport rate of acid (k(H)) must be greater than that of urea (k(S)) for oscillations in a urease-loaded membrane, bistability is possible for k(S) ≥ k(H).
School of Chemistry, University of Leeds , Leeds, LS2 9JT, U.K.
Tamás
T
Bánsági
Annette F
AF
Taylor
D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D016014:Linear Models; D008566:Membranes / Q000737:chemistry; D008956:Models, Chemical; D014508:Urea / Q000737:chemistry*; D014510:Urease / Q000737:chemistry*
D014508:Urea; D014510:Urease