Compare and contrast allosteric control versus covalent modification as effector

Question

Compare and contrast allosteric control versus covalent modification as effectors of enzyme activity. Address the following in your response:
a. Write reactions to show a general enzyme before and after allosteric control/covalent modification.
b. Describe what is directly responsible for creating the Compare and contrast allosteric control versus covalent modification as effectors of enzyme activity. Address the following in your response:
a. Write reactions to show a general enzyme before and after allosteric control/covalent modification.
b. Describe what is directly responsible for creating the Compare and contrast allosteric control versus covalent modification as effectors of enzyme activity. Address the following in your response:
a. Write reactions to show a general enzyme before and after allosteric control/covalent modification.
b. Describe what is directly responsible for creating the

Explanation / Answer

In allosteric modification, effectors bind to multiple subunits increasing the enzyme activity for substrate binding. Effector molecules bind to a site other than substrate binding site.

In covalent modification, enzymes are regulated by transfer of a molecule from donor to an amino acid side chain. This modification may activate or deactivate the enzyme.

Allosteric modification :

a) Phospho fructo kinase (PFK) controls a rate limiting step in glycolysis. When cellular ATP is high, ATP allosterically binds to PFK and inhibits the glycolysis process. ATP binds to an allosteric site other than active site and modifies the conformation of PFK. (b) In this reaction after ATP gets synthesised in excess it acts as a feedback inhibitor and binds to the allosteric site of PFK, thus stps the glycolysis process. (c) If cell utilises ATP or cellular ATP goes down, PFK starts synthesizing ATP through glycolysis.

Covalent modification :

a) Many enzymes are activated or inactivated by the transfer of inorganic phosphorous from a donor to an enzyme. Kinases add phosphorous and phosphatases remove the phosphorous from enzymes. Digestive enzymes remain as zymogens till they reach the site of action and they get converted to active forms by the addition of inorganic phosphorous.

b) Cellular conditions affect the activation of zymogens to active forms.

c) When the need is fulfilled by active forms of the enzyme, phosphatases remove the inorganic phosphorous from active enzyme and make them inactive again.

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