Portal de Periódicos da CAPES

Studies on the regulation of chloroplast fructose-1,6-bisphosphatase. Activation by fructose 1,6-bisphosphate

1980; Elsevier BV; Volume: 613; Issue: 2 Linguagem: Inglês

10.1016/0005-2744(80)90097-2

1878-1454

Claudio Chehebar, Ricardo A. Wolosiuk,

Diet, Metabolism, and Disease

Chloroplast fructose-1,6-bisphosphatase d-fructose 1,6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) isolated from spinach leaves, was activated by preincubation with fructose 1,6-bisphosphate. The rate of activation was slower than the rate of catalysis, and dependent upon the temperature and the concentration of fructose 1,6-bisphosphate. The addition of other sugar diphosphates, sugar monophosphates or intermediates of the reductive pentose phosphate cycle neither replaced fructose 1,6-bisphosphate nor modified the activation process. Upon activation with the effector the enzyme was less sensitive to trypsin digestion and insensitive to mercurials. The activity of chloroplast fructose-1,6-bisphosphatase, preincubated with fructose 1,6-bisphosphate, returned to its basal activity after the concentration of the effector was lowered in the preincubation mixture. The results provide evidence that fructose-1,6-bisophosphatase resembles other regulatory enzymes involved in photosynthetic CO2 assimilation in its activation by chloroplast metabolites.