title: Enzymatic activity of immobilized enzyme determined by isothermal titration calorimetry.
abstract: The activity of adsorbed beta-glucosidase onto spherical polyelectrolyte brushes (SPBs) is investigated by UV-Vis spectroscopy and isothermal titration calorimetry (ITC). By comparing the results of these two methods, we demonstrate that ITC is a precise method for the study of the activity of immobilized enzymes. The carrier particles used for immobilization here consist of a polystyrene core onto which poly(acrylic acid) chains are grafted. High amounts of enzyme can be immobilized in the brush layer at low ionic strength by the polyelectrolyte-mediated protein adsorption (PMPA). Analysis of the activity of beta-glucosidase was done in terms of Michaelis-Menten kinetics. Moreover, the enzymatic activity of immobilized enzyme is studied by ITC using cellobiose as substrate. All data show that ITC is a general method for the study of the activity of immobilized enzymes.
authors.affiliation: Physikalische Chemie I, University of Bayreuth, D-95440 Bayreuth, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Henzler
authors.forename: Björn
authors.initials: B
authors.lastname: Haupt
authors.forename: Matthias
authors.initials: M
authors.lastname: Ballauff
mesh_terms: D000818:Animals; D002151:Calorimetry / Q000379:methods*; D002417:Cattle; D004800:Enzymes, Immobilized / Q000378:metabolism*; D007700:Kinetics; D011137:Polystyrenes / Q000378:metabolism; D027861:Prunus / Q000201:enzymology*; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D013379:Substrate Specificity; D017186:Titrimetry; D001617:beta-Glucosidase / Q000378:metabolism*
chemical_list: D004800:Enzymes, Immobilized; D011137:Polystyrenes; D012710:Serum Albumin, Bovine; D001617:beta-Glucosidase