Surface coverage dictates the surface bio-activity of d-amino acidoxidase

ELISA HERRERA; CARLA E. GIACOMELLI

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014 vol. 117 p. 296 - 296

This work presents a systematic study on the relationship between the adsorption mechanism and thesurface bio-activity of d-amino acid oxidase (pkDAAO). This rational approach is based on measuringthe characteristic filling and relaxation times under different experimental conditions. With such a goal,real-time adsorption?desorption experiments at different degrees of surface coverage were performedtuning the electrostatic and hydrophobic interactions by changing the pH condition for the adsorptionand the substrate properties (silica or gold). Surface bio-activity was measured in situ by amperometryusing the bio-functional surface as the working electrode and ex situ by spectrophotometry. On both solidsubstrates, pkDAAO adsorption is a transport-controlled process, even under unfavorable electrostaticinteractions (charged protein and substrate with the same sign) due to the high percentage of basicamino acids in the enzyme. On silica, the relaxation step is electrostatic in nature and