2.2 Enzymes Flashcards
What is the equilibrium constant?
K = Kf/ Kr
Amount of substrate found at equilibruim
What is the transition state?
Intermediate moment during the reaction where old bonds are completely broken, and the new bonds are incompletely formed
How do enzymes lower the transition state energy of a reaction?
Proximity
Orientation
Microenvironment
What are cofactors?
Compounds involved in reactions, must be bound tightly (prosthetic groups) or loosely (coenzyme). Critical for catalysis reaction of the enzyme.
Define prosthetic group
cofactors that are tightly bound
Define coenzymes
cofactors that are loosely bound
Enzymatic pathways
Enzymes rarely operate alone: they are part of a chain of reactions = pathway
Pathways are important for making the final product
What do feedback mechanisms control?
Many metabolic pathways (inhibition on activation, depending on quantity/ nature of a certain enzyme part of the chain)
What is allosteric regulation?
When the product feedbacks and regulates the enzymes, interact away from the active site.
How is enzyme activity regulated by allosteric regulation?
Allosteric inhibitors can decrease the affinity of the enzyme for the substrate
Allosteric activators increases the affinity of the enzyme for the substrate
What mechanisms involving enzyme modification regulate enzyme activity?
Covalent modification, especially phosphorylation
Regulatory proteins and/ or nucleotides (binding)
Ion binding (ex : Ca2+)
Proteolysis
How does covalent modification control enzyme activity?
Phosphorylation and dephosphorylation
Explain the process of phosphorylation.
- require ATP as phosphate donor (produces ADP in addition)
- phosphate group links to serine, the online or tyrosine on the target protein
What are the two forms of kinase?
- serine/ threonine kinases
- tyrosine kinases
