Sesh 11: Regulating Protein Function Flashcards
Name 2 general ways to regulate enzyme function, short term.
- Change substrate/product concentration
2. Change enzyme conformation
Name 3 ways enzyme conformation can be changed.
- Allosteric regulation
- Covalent modification
- Proteolytic cleavage
Name 2 ways enzyme activity can be regulated long-term.
- Change rate of protein synthesis (induction/repression)
2. Alter rate of degradation (ubiquitin-proteasome pathway)
Allosteric activators increase the proportion of enzyme in what state?
R state.
Name an allosteric activator and an allosteric inhibitor of phosphofructokinase.
Activator= AMP or fructose-2,6-bisphosphate Inhibitor= ATP, citrate or H+
What is the most common form of protein modification?
Phosphorylation- form of covalent modification
What part of a protein is phosphorylated by kinases?
OH group of serine, threonine and/or tyrosine residues
What is a zymogen?
An inactive precursor that is converted by another enzyme into an active form of an enzyme.
How is proteolytic cleavage controlled?
Is irreversible, so is controlled by inhibitors that regulate protease activity.
Which enzyme is deficient in emphysema and what is its normal role?
Alpha-1 antitrypsin. Normally inhibits trypsin and other proteases.
How specific is trypsin?
Not very….has a very wide range of specificities, to cleave and activate a number of enzymes.
Which clotting factor cleaves prothrombin to its active form, thrombin?
Factor Xa
Which enzyme cleaves fibrinogen to fibrin?
Thrombin
How are blood clotting factors activated?
Activated from inactive zymogen form via proteolytic cleavage.
What are Gla domains, and what is their function within the clotting cascade?
Carboxyglutamate groups added on to clotting factors, allowing them to bind Ca2+, bringing clotting factors closer to each other and the site of damage.
