Base-catalyzed feedback in the urea-urease reaction.
The bell-shaped rate-pH curve coupled to production of base in the urea-urease reaction was utilized to give feedback-driven behavior: an acid-to-base pH clock (a kinetic switch), bistability and hysteresis between an acid/base state when the initial pH was adjusted by a strong acid, and aperiodic pH oscillations when the initial pH was adjusted by a weak acid in an open reactor. A simple model of the reaction reproduced most of the experimental results and provided insight into the role of self-buffering in the dynamics. This reaction suggests new possibilities in the development of biocompatible feedback to couple to pH-sensitive processes for bioinspired applications in medicine, engineering, or materials science.
Hu
Gang
G
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Pojman
John A
JA
Scott
Stephen K
SK
Wrobel
Magdalena M
MM
Taylor
Annette F
AF
D055162:Biocatalysis; D032701:Biomimetics; D004795:Enzyme Stability; D025461:Feedback, Physiological; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008956:Models, Chemical; D011485:Protein Binding; D014508:Urea / Q000378:metabolism*; D014510:Urease / Q000378:metabolism*
D014508:Urea; D014510:Urease