Designing an enzymatic oscillator: bistability and feedback controlled oscillations with glucose oxidase in a continuous flow stirred tank reactor.
The reaction of glucose with ferricyanide catalyzed by glucose oxidase from Aspergillus niger gives rise to a wide range of bistability as the flow rate is varied in a continuous flow stirred tank reactor. Oscillations in pH can be obtained by introducing a negative feedback on the autocatalytic production of H+ that drives the bistability. In our experiments, this feedback consists of an inflow of hydroxide ion at a rate that depends on [H+] in the reactor as k0[OH-]0[H+]/(K+[H+]). pH oscillations are found over a broad range of enzyme and ferricyanide concentrations, residence times (k0 (-1)), and feedback parameters. A simple mathematical model quantitatively accounts for the experimentally found oscillations.
Vanag
Vladimir K
VK
Department of Chemistry, MS 015, Brandeis University, Waltham, Massachusetts 02454, USA. vanag@brandeis.edu
Míguez
David G
DG
Epstein
Irving R
IR
D001234:Aspergillus niger / Q000201:enzymology; D019149:Bioreactors; D002384:Catalysis; D003198:Computer Simulation; D004795:Enzyme Stability; D005246:Feedback; D005292:Ferricyanides / Q000737:chemistry / Q000494:pharmacology; D005947:Glucose / Q000737:chemistry / Q000378:metabolism; D005949:Glucose Oxidase / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides; D008962:Models, Theoretical; D009991:Oscillometry
D005292:Ferricyanides; D006878:Hydroxides; C007931:hexacyanoferrate III; C031356:hydroxide ion; D005949:Glucose Oxidase; D005947:Glucose