title: pH wave-front propagation in the urea-urease reaction.
abstract: The urease-catalyzed hydrolysis of urea displays feedback that results in a switch from acid (pH ~3) to base (pH ~9) after a controllable period of time (from 10 to >5000 s). Here we show that the spatially distributed reaction can support pH wave fronts propagating with a speed of the order of 0.1-1 mm min(-1). The experimental results were reproduced qualitatively in reaction-diffusion simulations including a Michaelis-Menten expression for the urease reaction with a bell-shaped rate-pH dependence. However, this model fails to predict that at lower enzyme concentrations, the unstirred reaction does not always support fronts when the well-stirred reaction still rapidly switches to high pH.
authors.affiliation: School of Chemistry, University of Leeds, Leeds, United Kingdom.
authors.forename: Magdalena M
authors.initials: MM
authors.lastname: Wrobel
authors.affiliation: School of Chemistry, University of Leeds, Leeds, United Kingdom.
authors.forename: Tamás
authors.initials: T
authors.lastname: Bánsági
authors.affiliation: School of Chemistry, University of Leeds, Leeds, United Kingdom.
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Scott
authors.affiliation: School of Chemistry, University of Leeds, Leeds, United Kingdom. Electronic address: a.f.taylor@leeds.ac.uk.
authors.forename: Annette F
authors.initials: AF
authors.lastname: Taylor
authors.affiliation: Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana.
authors.forename: Chris O
authors.initials: CO
authors.lastname: Bounds
authors.affiliation: Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana.
authors.forename: Arturo
authors.initials: A
authors.lastname: Carranza
authors.affiliation: Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana.
authors.forename: John A
authors.initials: JA
authors.lastname: Pojman
mesh_terms: D004058:Diffusion; D005246:Feedback; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008956:Models, Chemical; D011485:Protein Binding; D014508:Urea / Q000378:metabolism*; D014510:Urease / Q000378:metabolism*
chemical_list: D014508:Urea; D014510:Urease