The Control Properties of Phosphofructokinase in Relation to the Respiratory Climacteric in Banana Fruit
AUTOR(ES)
Salminen, Seppo O.
RESUMO
Glucose 6-phosphate, fructose 6-phosphate, fructose 1, 6-diphosphate, and triose phosphates, and the enzymes phosphofructokinase, aldolase, and glucose 6-phosphate dehydrogenase were extracted from banana fruit (Musa cavendishii, Lambert var. Valery) at the (a) preclimacteric, (b) climacteric rise, (c) climacteric peak, and (d) postclimacteric stages of ripening. The level of fructose 1, 6-diphosphate increased 20-fold whereas the concentration of other intermediates changed no more than 2.5-fold between stages a and c. For these same extracts, phosphofructokinase activity increased 2.5-fold whereas the activity of glucose 6-phosphate dehydrogenase and aldolase changed only fractionally. Substrate saturation studies (fructose 6-phosphate) of phosphofructokinase activity showed a decrease in the [S]0.5 from 5.6 to 1.7 mM betwen stages a and c. The enzyme from both sources seems to be regulated by a negative cooperative effect with the control being more stringent in the enzyme from stage a. The difference in enzyme activity is consistent with the increase in respiratory activity between the two stages.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=541548Documentos Relacionados
- Succinoxidase Activity of Avocado Fruit Mitochondria in Relation to Temperature and Chilling Injury throughout the Climacteric Cycle 1
- The Climacteric in Ripening Tomato Fruit 1
- Regulation of Climacteric Respiration in Ripening Avocado Fruit 1
- The Climacteric Rise in Fruit Respiration as Controlled by Phosphorylative Coupling
- Organic Acids in the Ripening Banana Fruit 1