title: Activity of alkaline phosphatase adsorbed and grafted on "polydopamine" films.
abstract: The oxidation of dopamine in slightly basic solutions and in the presence of oxygen as an oxidant allows for the deposition of dopamine-eumelanin ("polydopamine") films on almost all kinds of materials allowing for an easy secondary functionalization. Molecules carrying nucleophilic groups like thiols and amines can be easily grafted on those films. Herein we show that alkaline phosphatase (ALP), as a model enzyme, adsorbs to "polydopamine" films and part of the adsorbed enzyme is rapidly desorbed in contact with Tris buffer. However a significant part of the enzyme remains irreversibly adsorbed and keeps some enzymatic activity for at least 2 weeks whereas ALP adsorbed on quartz slides is rapidly and quantitatively deactivated. In addition we estimated the Michaelis constant Km of the enzyme irreversibly bound to the "polydopamine" film. The Michaelis constant, and hence the affinity constant between paranitrophenol phosphate and ALP are almost identical between the enzyme bound on the film and the free enzyme in solution. Complementarily, it was found that "polydopamine" films display some phosphatase like catalytic activity.
authors.affiliation: Université de Strasbourg, Faculté de Chirurgie Dentaire, 1 Place de l'Hôpital, 67000 Strasbourg Cedex, France; Institut National de la Santé et de la recherche Médicale, Unité Mixte de Recherche 1121, 11 rue Humann, 67085 Strasbourg Cedex, France. Electronic address: vball@unistra.fr.
authors.forename: Vincent
authors.initials: V
authors.lastname: Ball
mesh_terms: D000327:Adsorption; D000469:Alkaline Phosphatase / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D011108:Polymers / Q000737:chemistry*
chemical_list: D007211:Indoles; D011108:Polymers; C568283:polydopamine; D000469:Alkaline Phosphatase
keywords: Alkaline phosphatase; Materials with catalytic activity; Stability versus time; “Polydopamine”