RESUMO
Larvae of the onion fly, Delia antiqua, have lower superoxide dismutase (SOD) activity when they are fed a defined synthetic diet that contains no copper or zinc. SOD activity was rapidly recovered when these larvae were fed onion bulbs. Addition of copper and zinc to the synthetic diet also led to the recovery of SOD activity. Results of an immunoblotting analysis using anti-D. antiqua CuZnSOD mouse monoclonal antibody suggest that this alteration of SOD activity is dependent on the amount of CuZnSOD.
Assuntos
Cobre/administração & dosagem , Dípteros/enzimologia , Superóxido Dismutase/metabolismo , Zinco/administração & dosagem , Animais , Anticorpos Monoclonais , Sulfato de Cobre/farmacologia , Dieta , Dípteros/crescimento & desenvolvimento , Indução Enzimática/efeitos dos fármacos , Larva/enzimologia , Larva/crescimento & desenvolvimento , Camundongos , Superóxido Dismutase/biossíntese , Superóxido Dismutase/imunologiaRESUMO
Most attempts to modify the properties of enzymes by amino acid substitution around the active sites have resulted in suppression of the biological activity, suggesting that the structure of natural enzymes should be almost optimized evolutionally to show the highest activity. In contrast, we found an interesting site of a well-known metalloendopeptidase, thermolysin (EC.3.4.24.4), where almost all the amino acid replacement causes a remarkable increase in the hydrolytic activity. Negative correlation between the activity and the thermal stability was observed. The flexibility around the substrate binding site is suggested to be a key to the correlation. Nature may have selected the amino acid at this site, which suppresses the flexibility of the molecule, to get the highest thermal stability at the expense of the activity.
