enzyme regualtion-14 Flashcards
What is the function of an isozyme
isozymes catalyze the same reaction but with different efficiencies by mix and matching subunits
what are some examples covalent protein modifications
Lipids: myristilation, farnesylation
nucelotides: ADP ribosylation
proteins: ubiquitination
small molecules:
gamma carboxylation, sulfation, acetylation, methylation, phosphorylation
How are carbohydrates covalently linked to other molecules and why are such linkages important
They are linked via O or N linkages
they help provide the greatest source of diversity to the proteome and compose sugars
why is phosphorylation activating
it is a thermodynamically favorable reaction
shape and charge are complementary
physiological processes dictate reaction rate
what is the difference between heteroallsotery and homoallostery
heteroallostery: effector molecule binds the substate binds to the allosteric site
homoallostery : cooperativity, each active site is different from its neighbor
What regulation strategy is exemplified by ATCase ad what moelcules are involved in this regualtion
allosteric regulation
CTP- binds causing a tense inhibited state
ATP- binds causing relaxed active state
How do the following actions affect Transcription
histone acetylation
histone phosphorylation
histone methylation
histone acetylation–> activates transcription
histone phosphorylation–> deactivates transcription
histone methylation- can activate or deactivate transcription
What are zymogens and how are they activated
zymogens are inactive forms of an enzymes that are activated by proteolytic cleavage
Why and how must chymotrypsin be proteolytically activated
must be activated to arrange the aa that will interact so the reaction can occur
The enzyme is cut in two places to make it active, the first cut is made by trypsin and is between ile and arg, the second cut is made by chymotrypsin and is between ser and leu
