Lecture 14 Flashcards
Metabolic enzymes are regulated by what 4 factors?
- Compartmentalization: different locations
- Enzyme Concentration: on/off switch
- Enzyme Activity: Volume control
- Hormone signals and second messengers: master regulators
Compare substrate level control with feedback control
Substrate level control: when the amount of product acts on a single reaction
Feedback control: when the amount of a produce targets a different step in a reaction pathway
Compare what activators and inhibitors promote
activators promote more products
inhibitors promote less products
Define Isozymes
Isozyme: a “mix and match” subunit that catalyzes the same reaction but with different efficiencies
Explain how tissue specificity is determined and how development is carried out
Tissue specificity is determined via compartmentalized isozymes
Development is carried out via temporal expression of isozymes
What can you test in a pt’s blood in order to try to determine if they have or have not had a heart attack?
you can test for the H4 isozyme of LDH
_____-_____ modifications create non proteinogenic AA’s
post-translational
State the function of reversible covalent modifications when they are affecting enzyme activity
they add 1 “functional group” to activate/inactivate an enzyme
what molecular group is the greatest source of diversity to the proteome?
carbohydrates
Myristic acid and farnesyl formation is an example of what kind of reversible covalent modification?
myristic acid and farnesyl are formed by performing reversible covalent modifications on lipids
ADP-ribose is an example of what kind of reversible covalent modification?
ADP-ribose is formed by performing reversible covalent modifications on nucleic acids
Ubiquitin is an example of what kind of reversible covalent modification?
ubiquitin is formed by performing reversible covalent modifications on proteins
State the 4 categories of reversible covalent modifications that can occur to carbohydrates
- O- vs N-linkages
- Composition of Sugars
- Branched vs Unbranched
- Length of an oligosaccharide
State and describe the 4 mechanisms that occur and describe why phosphorylation via kinases is activating
- Thermodynamics: ATP hydrolysis can drive unfavorable reactions
- Kinetics: physiologic processes dictate reaction rate
- Cell processes: ATP amounts dictated by metabolism (energy charge) signal transduction amplification (catalytic turnover)
- Shape and charge complementary: each phosphate adds (2-) charge and (3+) H-bonds
what is the significance of the name of a kinase?
the name of a kinase indicates on which AA the phosphate will be added
True or False:
Allosteric binding occurs in the active site of an enzyme. explain.
False
Allosteric binding DOES NOT occur at the active site
Compare Heteroallostery and Homoallostery
Heteroallostery: The effector binds at the allosteric site
Homoallostery: cooperativity
Describe the mechanism by which the generic regulation of ACTase is conducted
ACTase when CTP is present prefers the T (inactive state)
ACTase when ATP is present prefers the R (active state)
Describe what it means when one says “enzyme amount is the ON/OFF switch”.
since enzyme levels control the rate of protein synthesis, their level directly controls whether that protein is considered to be be “ON/OFF”
State the 2 levels of control that are possible via enzyme
Transcription regulation @ promoters
Translation regulation @ UTRs
Compare what histone acetylation promotes, what histone phosphorylation promotes, and what histone methylation promotes.
Histone acetylation promotes transcription
Histone phosphorylation prevents transcription
Histone methylation either promotes OR prevents Transcription
True or false:
mRNA levels do not correlate to protein levels. explain
true
miRNA’s and UTRs are what control translation. not mRNA levels.
What type of chromatin promotes transcription and what type discourages transcription?
euchromatin turns transcription on
heterochromatin turns transcription off
Name the 4 types of important enzymes that begin as zymogens
- proteases (digestive enzymes, Collagenase (development), and Caspases (apoptosis))
- Collagen
- Blood clotting factors
- Insulin/Hormones
Explain the activation of chymotrypsin from it’s inactive form
The inactive form of chymotrypsin is chymotrypsinogen which has it’s A, B, and C chains still linked
The active form is an A, B, and C chain of chymotrypsin that forms the (active) alpha-chymotrypsin
Trypsin conducts the first cleavage, between the A and B chains, to form Pie-chymotrypsin
Pie-Chymotrypsin conducts the second cleavage, between the B and C chains, to form Alpha-chymotrypsin
Define Zymogen
Zymogen: an inactive substance which is converted into an enzyme when activated by another enzyme.
