Lecture 14, Regulation (Ford) Flashcards
How are metabolic enzymes regulated?
Compartmentalization, enzyme concentration, enzyme activity, hormone signals
How can reactions be affected?
Substrate-level control or feedback control
What kind of reaction does substrate-level control act on?
Single reaction
What kind of reaction does feedback control act on?
Targets a different step in the pathway
How is product formation affected by feedback?
Activators promote more product; inhibitors prevent more products
What are isozymes?
Catalyze the same reaction but with different efficiencies
T or F: Isozymes are compartmentalized based on tissue specificity.
True.
During development, what kind of expression do isozymes utilize?
Temporal
What can be added via reversible covalent modification?
Functional groups
How would the addition of functional groups affect an enzyme?
Activate or deactivate the enzyme
What are some common functional group additions?
Myristic acid, farnesyl, nucleic acids, ubiquitin, carbohydrates, small molecules
What is the greatest source of diversity to the proteome?
Addition of carbohydrates
What are the sources of diversity when carbohydrates are added via covalent modifications?
O- vs. N- linkages, composition of sugars, branched vs. unbranched, length of oligosaccharide
What are some common small molecule additions?
Gamma-carboxylation, sulfation, acetylation, methylation, phosphorylation
T or F: Acetylation tends to be deactivating.
False. Acetylation tends to be activating.
What types of covalent modification can histones experience?
Acetylate, methylate, phosphorylate
Why is phosphorylation activating regarding thermodynamics?
ATP hydrolysis can drive unfavorable reactions (-deltaG)
Why is phosphorylation activating regarding kinetics?
Physiological processes dictate reaction rate
Why is phosphorylation activating regarding cell processes?
ATP amounts dictated by metabolism (energy charge); Signal transduction amplification (catalytic turnover)
Why is phosphorylation activating regarding shape and charge complementarity?
Each phosphate adds -2 charge and 3+ H bonds
T or F: Phosphatases remove phosphates, while kinases add phosphates.
True.
What does the name of a kinase indicate?
On which amino acid the phosphate will be added
T or F: A tyrosine kinase will add a phosphate to a serine.
False. A tyrosine kinase will add a phosphate to a tyrosine.
Where is covalent modification happening?
Allosteric site
