Allosteric Enzymes And Inhibitors

Question 1

Name the 3 different enzyme inhibitors

Answer 1

Reversible competitive
Reversible uncompetitive
Reversible no competitive

Question 2

Define a reversible competitive inhibitor

Answer 2

Binds reversibly to active site, High substrate conc outcompetes inhibitor from active site

Question 3

Define a reversible uncompetitive inhibitor

Answer 3

Inhibitor binds to the ES complex and when bound, does not allow product formation

Question 4

Define reversible noncompetitive inhibitor

Answer 4

Binds reversibly to site other than active site. Changes enzymes structural conformation.
Reduced enzyme catalytic activity
Affinity of enzyme for substrate unchanged.

Question 5

Define Allosteric

Answer 5

Enzyme catalytic activity altered by binding of Allosteric effector/modulator to different binding sites

Question 6

Outline what a Homotropic Allosteric effector is

Answer 6

Enzymes substrate
-multiple subunits with multiple active sites
-binding of substrate to one active site facilitates binding of substrate to other active sites

Question 7

Define heterotropic allosteric effector

Answer 7

Regulatory molecule that is not the enzymes substrate. Binds reversibly to Allosteric site (not active site)

Question 8

Outline regulation of enzyme activity

Answer 8

-Allosteric control
-proteolytic activation of zymogens
-transcriptional regulation
-reversible covalent modification
-tissue specific expression of isozymes

Question 9

What is Allosteric control

Question 10

Give examples of proteolytic activation of zymogens

Question 11

Outline transcriptional regulation

Question 12

Give examples of reversible covalent modification

Question 13

Outline tissues specific expression of isozymes

Question 14

Outline enzyme regulation by covalent modification

Answer 14

Phosphorylation by Ser/Thr kinase (eg, by cAMP activated protein kinase A or Tyr Kinases). Reversed by action of protein phosphatases