Enzymes lecture 5 Flashcards
The product of one enzyme controlled reaction becomes the ____ of the next reaction
Substrate
Regulatory enzymes are the enzymes that have a GREATER OR LESSER? effect on the overall rate of the sequence of reaction
Regulatory Enzymes
These enzymes exhibit changes in catalytic activity in response to certain signals
Their activity is controlled by interactions with ____-
Regulatory Enzymes
Other molecules
What are the 4 things that can accomplish regulation?
Small molecules (metabolites/cofactors)
Other proteins that bind to the enzyme
Covalent modification of enzyme
Zymogen is cleaved to form the active enzyme
The activity of regulatory enzymes have be controlled by small molecules such as ____ or ____
They act as ____ effectors or ______ modulators
Metabolites or cofactors
Allosteric effectors
Allosteric Modulators
What type of binding occurs with small molecules in enzymes like metabolites and cofactors?
What does it do the enzyme?
Noncovalent
Change its shape (more active or inhibited)
No allosteric enzymes follow M-M kinetics?
What dependence do they show?
No
Sigmoidal
Allosteric behavior (with small molecules) is observed in what type of proteins?
Multisubunits having quaternary structure
The modulator in allosteric effectors is often the substrate itself, when substrate and modulator are identical the regulatory enzyme is ___
Homotropic
A hypothetical enzyme has two identical subunits, each containing an active site. Each sub unit has a _____ state and ____ state conformation
When a substrate binds to one subunits, there is a change from ___ to _____
What does this do for affinity of substrate binding?
T and R state
T to R conformation
increases the affinity for substrate binding and reaction velocity
If a modulator and substrate are different, the enzyme is ___
An allosteric effector molecule OTHER than the substrate can also bind to the enzyme to inhibit or activate the enzyme by stabilizing the T or R state
Binding of the modulator triggers _____, the substrate can now bind the substrate with higher or lower affinity
Heterotropic
Triggers a conformational change
It can bond with greater affinity
This is an allosteric enzyme with 12 polypeptide chains organize into catalytic and regulatory subunits
It catalyzes the formation of N-carbamoylaspartate from ____ and ____
This reaction is the first step in a sequence of rxns which leads to the synthesis of ______ nucleotide, UMP a
Asptartate Transcarbamoylase
Aspartate and carbamoyl phosphate
Pyrimidine nucleotide, UMP
UMP can be converted by UTP to _____
It can then by aminated by ____ to give CTP
ATP
Glutamine
____ is an activator in bacteria
____ is an inhibitor of aspartate transcarbamoylae
ATP
CTP
The regulation by CTP is an example of ________
Feedback inhibition
