Enzyme Regulation Flashcards
What are four ways of regulating enzyme activity?
Association with a regulatory protein
Sequestration (compartmentation)
Allosteric Regulation
Covalent Modification
How does compartmentalization regulate enzyme activity?
Isolating the reaction substrate or product from competing reactions
Provides a favorable environment
E.g. Acetyl-CoA carboxylase
What are some properties of enzymes that allow them to be regulated?
-pH, Km
Availability of substrate
What is feedback inhibition?
First enzyme in a multi-step pathway inhibited by the final product of the pathway
What is allosteric regulation?
Binding of small molecules that can increase or decrease activity of the enzyme
What is a homotropic allosteric regulator?
An allosteric regulator of the enzyme that is also a substrate for the enzyme.
(E.g. oxygen for hemoglobin)
What is a heterotropic allosteric regulator?
Regulatory molecule that is not the enzyme’s substrate.
E.g. CTP and ATP for aspartate transcarbomylase
What type of V vs. [S] curve is displayed by allosteric enzymes?
Sigmoidal
What are the allosteric inhibitors and activators of aspartate transcarbamoylase?
CTP, an end product, inhibits it
ATP activates it
How do covalent modifications regulate metabolic flow?
Post translational modifications can activate or inhibit key metabolic enzymes.
What are two important types of regulatory modifications?
Phosphorylation and Acetylation
These are often reversible
What are three advantages to using post translational modification as a regulatory mechanism?
Rapid
Does not require new protein synthesis or degredation
Easily reversible
What are the target residues for phosphorylation?
Serine
Threonine
Tyrosine
What is the significance about the addition of a phosphate group during phosphorylation?
It adds two negative charges to the amino acid residue.
What is the function of lysine acetyltransferases?
Catalyze the transfer of the acetyl group of Acetyl-CoA to the e-amino groups of lysyl residues.
