- Phosphofructokinase 1
Photo=Phosphofructokinase 6PFK wpmp.png
fructose 6-phosphate+ ATP to fructose 1,6-bisphosphate+ ADP
Citric acid cycle, Glycolysis
Names=6-Phosphofructokinase, 6-Phosphofructo-1-kinase, Fructose-6-P 1-Kinase, Fructose-6-phosphate 1-Phosphotransferase
http://www.pdb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb50_4.html more details...] )] Phosphofructokinase-1 (PFK-1) is the most important regulatory
enzyme(EC number|22.214.171.124) of glycolysis. It is an allostericenzyme made of 4 subunits and controlled by several activators and inhibitors. PFK-1 catalyzes one of the important "committed" steps of glycolysis, the conversion of fructose 6-phosphateand ATP to fructose 1,6-bisphosphate and ADP. Enzymatic Reaction
This step is subject to extensive regulation since it is not only irreversible, but also because the original substrate is forced to proceed down the glycolytic pathway after this step. This leads to a precise control of glucose and the other
monosaccharides galactoseand fructosegoing down the glycolysis pathway. Before this enzyme's reaction, glucose-6-phosphatecan potentially travel down the pentose phosphate pathway, or be converted to glucose-1-phosphate and polymerized into the storage form Glycogen.
allostericallyinhibited by ATP and citrate (from the citric acid cycle) and its product. It is also inhibited by low pH to prevent the accumulation of hydrogen ions in muscle. The enzyme has two sites with different affinities for ATP which is both a substrate and an inhibitor.
allostericallyactivated by a high concentration of AMP, but the most potent activator is fructose 2,6-bisphosphate, which is also produced from fructose-6-phosphate by PFK2.
PFK is inhibited by
glucagonthrough repression of synthesis.
The precise regulation of PFK 1 prevents
glycolysisand gluconeogenesisfrom occurring simultaneously.
There are three phosphofructokinase genes in humans:
PFK2(converts fructose 6-phosphate to fructose 2,6-bisphosphate through on site, or the opposite, on another site)
*PFP (reversibly interconverts fructose 6-phosphate and fructose 1,6-bisphosphate using inorganic
pyrophosphate(rather than ATP)
fructose bisphosphatase(hydrolyses fructose 1,6-bisphosphate to fructose 6-phosphate)
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