Enzyme regulation Flashcards
What is allosteric regulation?
When the enzyme switches between 2 states in response to reversible binding of allosteric modulators
What types of modifications can regulate enzyme activity?
Can be reversible like phosphorylation or irreversible like proteolytic cleavage
Why do allosteric enzymes usually have more than 1 subunit?
Usually one subunit is catalytic and the other is the regulatory subunit and will interact with the modulator
What are homotropic enzymes?
The allosteric modulator is also the substrate. Ex. Hb and O2
What are heterotropic enzymes?
The allosteric modulator is a different compound than the substrate. Ex. Hb and BPG
What type of kinetics do allosteric enzymes show?
Sigmoidal. They show cooperativity
What is feedback inhibition?
Downstream products of a metabolic pathway act as allosteric modulators and inhibits an earlier step in the pathway
Which amino acid residues are sites for phosphorylation?
Serine, threonine, tyrosine, sometimes histidine
How does phosphorylation activate or inactivate proteins?
It adds a negative charge to the protein which can result in a conformational change or change the recognition site for a binding partner
How is activity controlled in proteins with multiple phosphorylation sites?
Get different activity levels depending on which site is phosphorylated, provides more precise regulation
What are 7 reversible modifications to proteins regulate their activity?
Phosphorylation Adenylylation Acetylation Myristoylation Ubiquitination ADP-ribosylation Methylation
Which two protein modifications are commonly seen in epigenetics?
Acetylation and methylation
Which amino acid are adenylyl modifications attached?
Tyrosine
What is myristoylation? What group are they attached to?
A fatty acid group attached to the N-terminus
What is a zymogen?
Inactive precursor of an enzyme that has an extra polypeptide chain that keeps it inactive
