Enzyme Regulation Flashcards
_____ ______ bind to the same site of the enzyme, the active site
competitive inhibitors
____ _____ bind from a different site than the active site and bring about conformational change
noncompetitive inhibitors
____ inhibitors decrease Kcat and change substrate binding (Km)
mixed
_____ inhibitors decrease Kcat but do not affect substrate binding
pure
what are the two types of noncompetitive inhibitors?
mixed and pure
A competitive inhibitor is similar in ___ and ____ to the normal subsrate
size, shape
A competitive inhibitor cannot undergo a ___ _____
chemical reaction
Inhibitors might make it so the substrate is ____ bound to the enzyme
loosely
Inhibitors decrease the ____ of the substrate/reaction
Vmax
The inhibitors binds irreversibly to the enzyme by ____ bonds
covalent
____ substrates generate a reactive group that forms a covalent bond during binding to the active site
suicide
Penicillin is an example of a ____ substrate
suicide
Penicillin forms a covalent bond with an enzyme involved in the synthesis of what?
bacterial cell walls
Enzyme ____ is the ability of an enzyme to catalyze one particular reaction
specificity
What hypothesis considers the enzyme as the lock and the substrate fits in as the key?
lock and key
What hypothesis considers that the enzyme’s active site is modified upon binding to the substrate?
induced fit
The substrate glucose is bound to the active site of what enzyme?
hexokinase
What are the four mechanisms of enzyme regulation?
genetic control, covalent modification, specialized controls, allosteric regulation
___ _____ is the amount of enzyme that is produced by a gene (whether the gene for the enzyme is present, permanently suppressed, etc.)
genetic control
___ ______ is the attachment of chemical groups such as phosphate groups
covalent modification
Zymogens, isozymes, and modular proteins are examples of what?
specialized controls
___ _____ is an inhibitor of activator binding to the enzyme at a site different than the active site
allosteric regualation
What donates the phosphate molecule in the attachment of a phosphate group via covalent modification?
ATP
Protein ____ is an enzyme that adds a phosphate group to an enzyme
kinase
protein ____ is an enzyme that removes a phosphate group from an enzyme
phosphatase
The enzyme is catalytically active when the phosphate is ____
removed
The enzyme is catalytically inactive when the phosphate is _____
attached
The phosphate group addition affects protein _____
folding
The ___ ____ ____-_____ is removed from the enzyme when adding a phosphate group
amino acid side-chain
Phosphate ____ the active site of an enzyme, making it inactive
closes
_____ are inactive precursors of enzymes or other proteins that acquire full activity by specific cleavage of one or more peptide bonds of the proteins
zymogens
insulin, proteolytic enzymes, and blood clotting factors are examples of what?
zymogens
_____ is generated by excision of a specific peptide from proinsulin
insulin
_____ is the active form of proinsulin
insulin
Insulin is the active form of _____
proinsulin
_____ _____ are synthesized as zymogens in the pancreas and stomach
prteolytic
__ ___ ____ are produced by activation of zymogens of clotting factors
blood clotting factors
Proteolytic enzymes break down what?
dietary protein
Insulin is activated by the ____ of specific peptides
removal
Trypsin originates in the ___
pancreas
Chymotrypsin originates in the _____
panceras
Chymotrypsin originates in the _____
pancreas
Carboxypeptidase originates in the _____
pancreas
Elastase originates in the ____
pancreas
Pepsin originates in the _____
stomach
what is the active protein of trypsinogen?
trypsin
what is the active protein of chymotrypsinogen?
chymotrypsin
what is the active protein of procarboxypeptidase?
carboxypetidase
what is the active protein of proelastase?
elastase
what is the active protein of pepsinogen?
pepsin
What is the zymogen of trypsin?
trypsinogen
What is the zymogen of chymotrypsin?
chymotrypsinogen
What is the zymogen of carboxypeptidase?
procarboxypeptidase
What is the zymogen of elastase?
proelastase
What is the zymogen of pepsin?
pepsinogen
In the proteolytic activation of chymotrypsinogen, peptide bonds are _____ at the ends
cut
Chymotrypsin attacks _____ in the proteolytic activation process
itself
___ chymotrypsin is the fully active form
alpha
Chymotrypsin’s proteins are connected by what type of bonds?
disulfide bonds
What are the two blood clot formation pathways?
extrinsic/tissue factor, intrinsic/contact activation
Fibrinogen is ___ in blood
soluble
Fibrin is ______ in blood
insoluble
Fibrin forms ___ ____
blood clots
_______ activates blood clotting factors in the intrinsic pathway
proteases
_____ are forms of an enzyme that differ in their quaternary structure with different numbers of distinct polypeptide units
isozymes
Lactate dehydrogenase is an example of what ?
isozyme
There are ____ different subunits of LDH
5
____ _____ LDH is mainly A4 isozyme
skeletal muslce
Skeletal muscle LDH produces ____ ______ in ____ conditions
lactic acid, anaerobic
___ ____ LDH is mainly B4 isozyme
heart muscle
Heart muscle LDH uses ___ ____ in _____ conditions
lactic acid, aerobic
The two isozymes of LDH work in ____ directions
opposite
___ ____ are proteins that bind to enzymes and influence their activity
modulator proteins
modulator proteins ___ ___ the active site of enzymes
cover up
cAMP dependent protein kinases are examples of what?
modulator proteins
in cAMP dependent protein kinases, catalytic subunits are what part?
the enzyme
in cAMP dependent protein kinases, regulatory subunits are what part?
modulator proteins (that bind to the C subunits)
in cAMP dependent protein kinases, the R subunits ______ C subunit activity
inhibit
The modulator protein prevents ____ from binding to the active site and therefore stops product molecules from being made
substrates
cAMP dependent protein kinase is active when R subunits are _____
disconnected
___ ____ is the inhibition or activation of enzyme activity through noncovalent binding of small molecules to a site different than the active site
allosteric regulation
____ _____ is when the final product binds to the first enzyme to prevent further synthesis of the product
feedback inhibition
Feedback inhibition is what type of reguation?
non-competitive
What is the graph shape of allosteric enzymes?
sigmoid/S shaped curves
What is the s shaped curve of allosteric enzymes caused by?
cooperative binding
For an allosteric enzyme, the binding of the first substrate molecule makes it ______ for other substrate molecules to bind to different subunits
easier
Allosteric effectors change the ______ structure of the subunit polypeptides and/or change the subunit interactions
3D
For an allosteric enzyme, the more substrate there is the more ____ states are converted into the ___ state
T (taut), R (relaxed)
For allosteric enzymes, the ___ state is inactive
T (taut)
For allosteric enzymes, the ___ state is active
R (relaxed)
A dimeric protein is how many subunits?
2
