Regulation of Enzymes

Question 1

Feedback inhibition

Answer 1

An enzymes is inhibited by high levels of a product made from another enzyme later in the pathway

Question 2

Reversible Inhibition

Answer 2

The ability to replace the inhibitor with a compound of greater affinity or remove it using mild lab treatment

Question 3

Competitive inhibition

Answer 3

Inhibitor is similar to the substrate and binds at the active site.
Blocks substrate from binding
Can be overcome by adding more substrate

v max is unchanged
km increases

Same y-intercept
Different slopes

Question 4

Uncompetitive inhibition

Answer 4

Inhibitor binds only with the enzyme substrate complex

v max decreases
km decreases

Same slope
Different y-intercept

Question 5

Non competitive inhibition

Answer 5

Inhibitor binds with equal affinity to the enzyme and enzyme-substrate complex
Binds to allosteric site rather than active site
Cannot be overcome by adding more substrate

v max decreases
km unchanged

same x-intercept
different slopes

Question 6

Mixed inhibition

Answer 6

Inhibitor binds with unequal affinity to the enzyme and the enzyme-substrate complex

v max decreases
km increases or decreases depending on if inhibitor has a higher affinity for the enzyme or complex

Question 7

Irreversible inhibition

Answer 7

Alters enzyme that the active site is unavailable for a prolonged duration or permanently

Question 8

Suicide inhibitor

Answer 8

A substrate analogue that binds irreversibly to the active site via covalent bond

Question 9

Allosteric sites

Answer 9

Non-catalytic regions that bind regulators and regulate the availability of the active site

Question 10

Allosteric enzymes

Answer 10

Alternate between active and inactive form
Active: more available
Inactive: less available
Do not follow M-M kinetics

Question 11

Allosteric effectors

Answer 11

Bind sat the allosteric site and induces a change in the conformation of the enzyme so the substrate can no longer bind active site

k-type:
allosteric inhibitor increases k(1/2)
allosteric activator decreases k (1/2)

v-type:
allosteric inhibitor decreases v max
allosteric activator increases v max

Question 12

Homotropic effector

Answer 12

Allosteric regulator that is also the substrate
Example: oxygen is homotropic allosteric regulator of hemoglobin

Question 13

Heterotropic effector

Answer 13

An allosteric regulator molecule that is different from substrate

Question 14

Glycosylation

Answer 14

Covalent modification with carbohydrate

Question 15

Zymogens

Answer 15

Enzymes activated by protolysis

Question 16

Feed forward regulation

Answer 16

Enzymes regulated by intermediates that precede the enzyme in the pathway