RESUMO
BACKGROUND: Glucose oxidase enzyme may be a suitable model for studying the effect of low temperatures on structural and functional properties of biomacromolecules. OBJECTIVE: The research aim was to study the freeze-thawing effect on glucose oxidase isolated and immobilized by cross-linking with glutaraldehyde METHODS: Effects of freezing rates on conformation and activity of glucose oxidase isolated and cross-linked in solution with gluteraldehyde was studied. RESULTS: Freezing with slow rate (2 degree C per min) induces significant protein aggregation, activity reduction and conformational changes in polar and hydrophobic regions. Freezing at 100 degree C per min, however, causes conformational changes primarily in polar regions, insignificant aggregation, depending on the number of freeze-thawing cycles and increases enzyme activity. CONCLUSION: With the rise in glucose oxidase concentration in solution the low temperature-induced destabilization effect is reduced both during low and rapid freezing. At the slow cooling rate, cross-linking with glutaraldehyde results in more conformation alterations in polar regions of proteins, accompanied with an increase in enzyme activity.
Assuntos
Enzimas Imobilizadas/química , Proteínas Fúngicas/química , Glucose Oxidase/química , Aspergillus niger/química , Aspergillus niger/enzimologia , Temperatura Baixa , Reagentes de Ligações Cruzadas/química , Congelamento , Glutaral/química , Interações Hidrofóbicas e Hidrofílicas , Cinética , Conformação Proteica , SoluçõesRESUMO
The effect of NaCl concentration (0-2 M) on the absorption spectrum and enzymic activity of cytochrome oxidase built in lecithin liposome has been studied at 24 and 8 degrees C. It is shown that at 0,8 M NaCl concentration a conformational transition occurs that leads to the enzyme inactivation. The relationship between protein conformation and liposome state has been established.
Assuntos
Complexo IV da Cadeia de Transporte de Elétrons/efeitos dos fármacos , Cloreto de Sódio/farmacologia , Animais , Bovinos , Complexo IV da Cadeia de Transporte de Elétrons/administração & dosagem , Complexo IV da Cadeia de Transporte de Elétrons/química , Lipossomos , Conformação Proteica , Relação Estrutura-Atividade , TemperaturaRESUMO
The effect of freezing-thawing on cytochrome oxidase from cattle heart was studied. The enzyme was characterized for its activity, absorption spectra, temperature perturbation differential spectra and conformational transitions. A decrease in the activity and conformational changes depend on the composition of the buffer system and the presence of potassium and sodium chlorides in the solution.
