ABSTRACT
A supramolecular approach was used for adsorbing a monolayer of adamantane-modified phenylalanine dehydrogenase on beta-cyclodextrin-coated Au electrodes. The enzyme electrode (poised at +200 mV vs. Ag/AgCl) showed a linear amperometric response up to 3 mM L-phenylalanine (L-Phe) with a lower detection limit of 15 microM. The reversible nature of this immobilization approach was confirmed.
Subject(s)
Amino Acid Oxidoreductases/chemistry , Biosensing Techniques/instrumentation , Electrochemistry/instrumentation , Microelectrodes , Phenylalanine/analysis , beta-Cyclodextrins/chemistry , Bacillus/enzymology , Biosensing Techniques/methods , Coated Materials, Biocompatible/chemistry , Enzymes, Immobilized/chemistry , Equipment Design , Equipment Failure Analysis , Gold/chemistry , Multiprotein Complexes/chemistry , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
A mono-aminated dextran derivative was attached to Bacillus badius phenylalanine dehydrogenase via a carbodiimide-catalyzed reaction. The optimum temperature for the conjugate was 10 degrees C higher than for native enzyme, and its thermostability was improved by 8 degrees C. The activation free energy of thermal inactivation at 45 degrees C was increased by 16.8 kJ/mol. The improved conformational stability of the modified enzyme was confirmed by fluorescence spectroscopy.