Steady-state oxidation of cholesterol catalyzed by cholesterol oxidase in lipid bilayer membranes on platinum electrodes

Michael P. Bokoch, Anando Devadoss, Mariela S. Palencsár, James Burgess

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Cholesterol oxidase is immobilized in electrode-supported lipid bilayer membranes. Platinum electrodes are initially modified with a self-assembled monolayer of thiolipid. A vesicle fusion method is used to deposit an outer leaflet of phospholipids onto the thiolipid monolayer forming a thiolipid/lipid bilayer membrane on the electrode surface. Cholesterol oxidase spontaneously inserts into the electrode-supported lipid bilayer membrane from solution and is consequently immobilized to the electrode surface. Cholesterol partitions into the membrane from buffer solutions containing cyclodextrin. Cholesterol oxidase catalyzes the oxidation of cholesterol by molecular oxygen, forming hydrogen peroxide as a product. Amperometric detection of hydrogen peroxide for continuous solution flow experiments are presented, where flow was alternated between cholesterol solution and buffer containing no cholesterol. Steady-state anodic currents were observed during exposures of cholesterol solutions ranging in concentration from 10 to 1000 μM. These data are consistent with the Michaelis-Menten kinetic model for oxidation of cholesterol as catalyzed by cholesterol oxidase immobilized in the lipid bilayer membrane. The cholesterol detection limit is below 1 μM for cholesterol solution prepared in buffered cyclodextrin. The response of the electrodes to low density lipoprotein solutions is increased upon addition of cyclodextrin. Evidence for adsorption of low density lipoprotein to the electrode surface is presented.

Original languageEnglish (US)
Pages (from-to)47-55
Number of pages9
JournalAnalytica Chimica Acta
Volume519
Issue number1
DOIs
StatePublished - Aug 9 2004
Externally publishedYes

Fingerprint

Cholesterol Oxidase
Lipid bilayers
Lipid Bilayers
Membrane Lipids
Platinum
platinum
Electrodes
electrode
lipid
Cholesterol
membrane
oxidation
Oxidation
Membranes
Cyclodextrins
hydrogen peroxide
LDL Lipoproteins
Hydrogen Peroxide
Buffers
vesicle

Keywords

  • Cholesterol oxidase
  • Electrode
  • Lipid bilayer
  • Lipoprotein

ASJC Scopus subject areas

  • Analytical Chemistry
  • Environmental Chemistry
  • Biochemistry
  • Spectroscopy

Cite this

Steady-state oxidation of cholesterol catalyzed by cholesterol oxidase in lipid bilayer membranes on platinum electrodes. / Bokoch, Michael P.; Devadoss, Anando; Palencsár, Mariela S.; Burgess, James.

In: Analytica Chimica Acta, Vol. 519, No. 1, 09.08.2004, p. 47-55.

Research output: Contribution to journalArticle

Bokoch, Michael P. ; Devadoss, Anando ; Palencsár, Mariela S. ; Burgess, James. / Steady-state oxidation of cholesterol catalyzed by cholesterol oxidase in lipid bilayer membranes on platinum electrodes. In: Analytica Chimica Acta. 2004 ; Vol. 519, No. 1. pp. 47-55.
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