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PFK is about 300 amino acids in length, and structural studies of the bacterial enzyme have shown it comprises two similar (alpha/beta) lobes: one involved in ATP binding and the other housing both the substrate-binding site and the allosteric site (a regulatory binding site distinct from the active site, but that affects enzyme activity). The identical tetra-mer subunits adopt 2 different conformations: in a 'closed' state, the bound magnesium ion bridges the phosphoryl groups of the enzyme products (ADP and fructose-1,6- bisphosphate); and in an 'open' state, the magnesium ion binds only the ADP[4], as the 2 products are now further apart. These conformations are thought to be successive stages of a reaction pathway that requires subunit closure to bring the 2 molecules sufficiently close to react.
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What is phosphofructokinase?
Phosphofructokinase (PFK) is an enzyme that generates energy from carbohydrates during physical activity.
Phosphofructokinase is an important control enzyme in the regulation of cellular respiration of cellular respiration What is statement that describes a function of phosphofructokinase?
it is an allosteric enzyme.
What blocks enzyme activity by binding to allosteric site of an enzyme causing the enzyme's active site to change shape?
An allosteric inhibitor stops enzyme activity by binding to an allosteric site and causing the conformation of the enzyme to change.
What would be unlikely to contribute to the substrate specificity of an enzyme?
The allosteric site is distinct from the active site, and does not affect the substrate specificity of the enzyme
How do allosteric regulation and competitive inhibition compare?
A competitive inhibition and allosteric regulation both involves an inhibitor molecule binding to the enzyme at a different area. The difference between the two is that allosteric inhibitors are modulator molecules which bind somewhere besides the catalytic activity.
What is phosphofructokinase?
Phosphofructokinase (PFK) is an enzyme that generates energy from carbohydrates during physical activity.
Phosphofructokinase is an important control enzyme in the regulation of cellular respiration of cellular respiration What is statement that describes a function of phosphofructokinase?
it is an allosteric enzyme.
What is found in allosteric enzymatic regulation?
An allosteric enzyme is one in which the activity of the enzyme can be controlled by the biniding of a molecule to the "allosteric site". This really just means somewhere other than the active site. Thus allosteric control of an enzyme can be classed in two ways. A positive allosteric modification is the binding of a molecule to the enzyme which increase the rate of reaction. Sort of like catalysing the catalysing effect of an enzyme. Obviously the opposite is true of negative allosteric modification. A good example for this is the activity of phosphofructokinase, which is promoted by a high AMP concentration, and inhibited by a high ATP concentration. This should make sense if you think about the action of a kinase etc.
What blocks enzyme activity by binding to allosteric site of an enzyme causing the enzyme's active site to change shape?
An allosteric inhibitor stops enzyme activity by binding to an allosteric site and causing the conformation of the enzyme to change.
What is characteristic of allosteric effectors?
Allosteric effectors may not resemble the enzyme's substrates.
Which of the following choices will result in continuous glycolysis?
Loss of allosteric binding site for ATP on phosphofructokinase-1 (PFK-1)
What statement is characteristic of allosteric effectors?
Allosteric effectors may not resemble the enzyme's substrates.
An enzyme whose activity is affected when a molecule binds to a certain site other than the active site is called?
an allosteric enzyme
Does the allosteric effect in an enzyme change the enzyme's function?
allosteric effectors have their own specific sites for binding to enzyme. they can bring positiveor negative effect. that depends on the natre of effector.
The particular region of an enzyme molecule that combines with the substrate it acts upon is called what?
The area where a molecule other than substrate can attach is called the allosteric site.
Which enzyme catalyzes the rate-limiting step of glycolysis?
Phosphofructokinase (PFK)
What is the allosteric inhibitor?
The inhibitor which binds or attached with the allosteric site of enzyme k/n as A.I ... BY "NAHEED KHATTI "
