Abstract
How fructose 2,6-bisphosphate and metabolic intermediates interact to regulate the activity of the cytosolic fructose 1,6-bisphosphatase in vitro has been investigated. Mg(2+) is required as an activator. There is a wide pH optimum, especially at high Mg(2+). The substrate dependence is not markedly pH dependent. High concentrations of Mg(2+) and fructose 1,6-bisphosphate are inhibitory, especially at higher pH. Fructose 2,6-bisphosphate inhibits over a wide range of pH values. It acts by lowering the maximal activity and lowering the affinity for fructose 1,6-bisphosphate, for which sigmoidal saturation kinetics are induced, but the Mg(2+) dependence is not markedly altered. On its own, adenosine monophosphate inhibits competitively to Mg(2+) and noncompetitively to fructose 1,6-bisphosphate. In the presence of fructose 2,6-bisphosphate, adenosine monophosphate inhibits in a fructose 1,6-bisphosphate-dependent manner. In the presence of adenosine monophosphate, fructose 2,6-bisphosphate inhibits in Mg(2+)-dependent manner. Fructose 6-phosphate and phosphate both inhibit competitively to fructose 1,6-bisphosphate. Fructose 2,6-bisphosphate does not affect the inhibition by phosphate, but weakens inhibition by fructose 6-phosphate. Dihydroxyacetone phosphate and hydroxypyruvate inhibit noncompetitively to fructose 1,6-bisphosphate and to Mg(2+), but both act as activators in the presence of fructose 2,6-bisphosphate by decreasing the S(0.5) for fructose 1,6-bisphosphate. A model is proposed to account for the interaction between these effectors.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 20
Claim · model-written summary
Magnesium was required to activate cytosolic fructose 1,6-bisphosphatase.
Not reportedTaxon
Verbatim
e0“Mg(2+) is required as an activator.”
Claim · model-written summary
The enzyme had a wide pH optimum, especially at high magnesium.
Not reportedTaxon
Verbatim
e0“There is a wide pH optimum, especially at high Mg(2+).”
Claim · model-written summary
Substrate dependence varied little with pH.
Not reportedTaxon
Verbatim
e0“The substrate dependence is not markedly pH dependent.”
Claim · model-written summary
High magnesium and fructose 1,6-bisphosphate inhibited activity, especially at higher pH.
- Treatment
- High concentrations of Mg(2+) and fructose 1,6-bisphosphatee0
- Outcome
- inhibitorye0
- Direction
- inhibitorye0
- Qualifier
- especially at higher pHe0
Not reportedTaxonComparator
Verbatim
e0“High concentrations of Mg(2+) and fructose 1,6-bisphosphate are inhibitory, especially at higher pH.”
Claim · model-written summary
Fructose 2,6-bisphosphate inhibited activity across a wide pH range.
- Treatment
- Fructose 2,6-bisphosphatee0
- Outcome
- inhibitse0
- Direction
- inhibitse0
- Qualifier
- wide range of pH valuese0
Not reportedTaxonComparator
Verbatim
e0“Fructose 2,6-bisphosphate inhibits over a wide range of pH values.”
Claim · model-written summary
Fructose 2,6-bisphosphate lowered maximal activity.
Not reportedTaxon
Verbatim
e0“It acts by lowering the maximal activity and lowering the affinity for fructose 1,6-bisphosphate”
Claim · model-written summary
Fructose 2,6-bisphosphate lowered affinity for fructose 1,6-bisphosphate.
Not reportedTaxon
Verbatim
e0“lowering the affinity for fructose 1,6-bisphosphate”
Claim · model-written summary
Fructose 2,6-bisphosphate induced sigmoidal substrate saturation kinetics without markedly altering magnesium dependence.
Not reportedTaxon
Verbatim
e0“for which sigmoidal saturation kinetics are induced, but the Mg(2+) dependence is not markedly altered.”
Claim · model-written summary
AMP inhibited competitively against magnesium.
- Outcome
- inhibits competitively to Mg(2+)e0
Not reportedTaxon
Verbatim
e0“On its own, adenosine monophosphate inhibits competitively to Mg(2+)”
Claim · model-written summary
AMP inhibited noncompetitively against fructose 1,6-bisphosphate.
- Outcome
- noncompetitively to fructose 1,6-bisphosphatee0
Not reportedTaxon
Verbatim
e0“noncompetitively to fructose 1,6-bisphosphate.”
Claim · model-written summary
With fructose 2,6-bisphosphate present, AMP inhibition depended on fructose 1,6-bisphosphate.
Not reportedTaxon
Verbatim
e0“In the presence of fructose 2,6-bisphosphate, adenosine monophosphate inhibits in a fructose 1,6-bisphosphate-dependent manner.”
Claim · model-written summary
With AMP present, fructose 2,6-bisphosphate inhibition depended on magnesium.
Not reportedTaxon
Verbatim
e0“In the presence of adenosine monophosphate, fructose 2,6-bisphosphate inhibits in Mg(2+)-dependent manner.”
Claim · model-written summary
Fructose 6-phosphate inhibited competitively against fructose 1,6-bisphosphate.
Not reportedTaxon
Verbatim
e0“Fructose 6-phosphate and phosphate both inhibit competitively to fructose 1,6-bisphosphate.”
Claim · model-written summary
Phosphate inhibited competitively against fructose 1,6-bisphosphate.
Not reportedTaxon
Verbatim
e0“Fructose 6-phosphate and phosphate both inhibit competitively to fructose 1,6-bisphosphate.”
Claim · model-written summary
Fructose 2,6-bisphosphate did not affect phosphate inhibition.
Not reportedTaxon
Verbatim
e0“Fructose 2,6-bisphosphate does not affect the inhibition by phosphate”
Claim · model-written summary
Fructose 2,6-bisphosphate weakened inhibition by fructose 6-phosphate.
Not reportedTaxon
Verbatim
e0“weakens inhibition by fructose 6-phosphate.”
Claim · model-written summary
Dihydroxyacetone phosphate inhibited noncompetitively against substrate and magnesium.
Not reportedTaxon
Verbatim
e0“Dihydroxyacetone phosphate and hydroxypyruvate inhibit noncompetitively to fructose 1,6-bisphosphate and to Mg(2+)”
Claim · model-written summary
Hydroxypyruvate inhibited noncompetitively against substrate and magnesium.
Not reportedTaxon
Verbatim
e0“Dihydroxyacetone phosphate and hydroxypyruvate inhibit noncompetitively to fructose 1,6-bisphosphate and to Mg(2+)”
Claim · model-written summary
Dihydroxyacetone phosphate acted as an activator with fructose 2,6-bisphosphate by decreasing substrate S(0.5).
Not reportedTaxon
Verbatim
e0“Dihydroxyacetone phosphate and hydroxypyruvate inhibit noncompetitively to fructose 1,6-bisphosphate and to Mg(2+), but both act as activators in the presence of fructose 2,6-bisphosphate by decreasing the S(0.5) for fructose 1,6-bisphosphate.”
Claim · model-written summary
Hydroxypyruvate acted as an activator with fructose 2,6-bisphosphate by decreasing substrate S(0.5).
Not reportedTaxon
Verbatim
e0“Dihydroxyacetone phosphate and hydroxypyruvate inhibit noncompetitively to fructose 1,6-bisphosphate and to Mg(2+), but both act as activators in the presence of fructose 2,6-bisphosphate by decreasing the S(0.5) for fructose 1,6-bisphosphate.”