RESUMO
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.
Assuntos
Aminoácido Oxirredutases/química , Técnicas Biossensoriais/instrumentação , Eletroquímica/instrumentação , Microeletrodos , Fenilalanina/análise , beta-Ciclodextrinas/química , Bacillus/enzimologia , Técnicas Biossensoriais/métodos , Materiais Revestidos Biocompatíveis/química , Enzimas Imobilizadas/química , Desenho de Equipamento , Análise de Falha de Equipamento , Ouro/química , Complexos Multiproteicos/química , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
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.