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34 Cards in this Set
- Front
- Back
the activity of an enzyme is dependent up the integrity of its ____
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fold
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what is a common way to reducing the amount of active enzyme
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focusing on the integrity of its fold
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how do you overcome a covalent modification of an enzyme
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de novo synthesis
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how can proteolysis activate an enzyme?
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enzyme might be "pro enzyme" which has an extra domain that keeps it inactive and when you remove it the protein actually becomes active
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where can you covalently add small molecules that change the function of an enzyme
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commonly on the R group
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______ is a well characterized common covalent modification that can be rapidly reversed
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phosphorylation
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what are some other common covalent modifications of enzymes
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phosphorylation
N glycosylation O glycosylation Hydroxylation Carboxylation |
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what R group is commonly modified by phosphorylation?
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resideus with hydroxyl
ser thr tyr |
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what R group is commonly modified by N glycosylation
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Asn
RNHsugar |
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what R group is commonly modified by O glycosylation
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RO sugar
ser thr |
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what R group is commonly modified by hydroxylation
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hydroxl group added to R group
Pro lys |
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what R group is commonly modified by carboxylation
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COOH added to R group
glu |
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_____ _____ is a common cellular strategy to regulate biosynthetic pathways
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feedback inhibition
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a _____ site is a site that is physically separated from the active site but that when occupied by a ligand, alters the catalytic ctivity of the enzyme
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allosteric
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do allosteric inhibitors follow MM?
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no!
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_______ enzymes are almost always comprised of more than one subuit, and complex interactions occur between these subunits that allow events occurring on one subunit to be communicated to another subunit
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allosteric
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what is the shape of an allosteric enzyme graph
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sigmoid S
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explain T and R states
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T is tense and substrate binding is very poor and relaxed is when substrate binds well and is enzymatically active
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an allosteric inhibitor tends to stabilize the __ state thus making the sigmoid curve more extreme
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T
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when might allosteric regulation look more like MM curve
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allosteric activators
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what is our important model of allosteric regulation
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CTP or cytidine triphosphate
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Describe the pathway to CTP
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aspartate + carbamoyl phsophate --> using ATCASE and several reactions + 2ATP make CTP
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ATCase is made up of how many subunits
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12
6 are catalytic 6 are regulatory |
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Binding of the first aspartate of a ATCase is difficult because
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it can only bind to the T state
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____ will be an allosteric inhibitor of ATCAase
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CTP
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Binding of CTP to ATCase stabilizes which state of the enzyme
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T
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will adding more CTP increase or decrease K.5
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increase! this means it actually slows it down (less affinity)
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In the case of the CTP allosteric pathway, what does adding ATP do
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ATP acts as an activator-- decreases K.5
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_____ are two or more forms of an enzyme that catalyze a given reaction in cells
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isoenzymes
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what is an example of an isoenzyme
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LDH
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what are the two isoenzyme forms of LDH
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M and H
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What are the possible combos of LDH
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M4, M3H, M2H2, M1H3, H4
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explain the two difference from H4 and M4 in LDH
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H4 has higher affinity for substrates and is allosterically inhibited by pyruvate
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where do you find more H subunits of LDH? M subunits?
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H in heart
M in skeletal muscle and liver |