CHAPTER 7 Flashcards
A non-allosteric protein that binds oxygen independently.
Myoglobin
An allosteric protein that binds oxygen cooperatively.
Hemoglobin
An allosteric enzyme that exhibits cooperative binding similar to hemoglobin.
Aspartate transcarbamoylase (ATCase)
Proteins that change their shape in response to a signal, leading to changes in function. Examples include hemoglobin and ATCas
Allosteric proteins
Myoglobin
Hemoglobin
Aspartate transcarbamoylase (ATCase)
Allosteric proteins
Catalyzes the first step in the biosynthesis of cytidine triphosphate (CTP), a nucleotide needed for RNA and DNA synthesis.
ATCase function
An energy-intensive process involving multiple steps.
Pathway producing nucleotides
This is an excellent example of how metabolic pathways are controlled to prevent overproduction of essential compounds.
ATCase regulation
A regulatory mechanism that shuts down an entire metabolic pathway when the final product is in excess.
A regulatory mechanism where the end product of a pathway inhibits the first enzyme in the pathway, preventing overproduction.
Feedback inhibition
An allosteric enzyme that catalyzes the first step in the biosynthesis of cytidine triphosphate (CTP).
ATCase
An inhibitor of ATCase, demonstrating feedback inhibition.
CTP
cytidine triphosphate
An oligomer whose biological activity is affected by other substances binding to it changes the enzymes activity by altering its quaternary structure.
Allosteric enzyme
A substance that modifies the behavior of an allosteric enzyme.
Allosteric effector
A type of allosteric effector that increases the enzyme’s activity.
Allosteric activator
A type of allosteric effector that decreases the enzyme’s activity.
Allosteric inhibitor
Indicates allosteric behavior in enzyme kinetics.
Sigmoidal curve
Both CTP and ATP bind to the same site on ATCase, but CTP is an inhibitor while ATP is an activator
ATCase regulation by CTP and ATP
When CTP is in short supply, ATP binding ______ ATCase activity of the enzyme.
ATP effect on ATCase
Increases
Models for allosteric enzymes
The two main models are the Concerted Model (1965) and the Sequential Model (1966).