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CBFM Final > Enzymes And RegulationOf Enzyems > Flashcards

Enzymes And RegulationOf Enzyems Flashcards

1
Q

All enzymes are proteins except

A

Ribozymes
-this is a catalytic ribonucleic acid triggering catalysis of RNA processing

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2
Q

Enzymes ___ transition state

A

Stabilize

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3
Q

If there were no enzyme how would the reaction proceed

A

Super slow or not at all
And it would take a tonnnn more energy

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4
Q

Εnzymes change the ____ energy but not the ______ energy

A

Activation

Overall

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5
Q

Enzymes _____ the rate of exergonic reactions by lowering the _______

A

Increase

Activation energy of the reaction

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6
Q

What 2 models describe the way enzymes work with substrates

A

Lock and key

Induced fit

See slide 8 W7

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7
Q

Which model is more common

A

Induced fit

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8
Q

What do enzymes need for catalysis

A

Active sites aka groove aka cleft

Cofactors - metal ions

Coenzymes - prosthetic groups

Compartmentalization

Specificity

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9
Q

Steps of induced fit

A

1 - enzyme active site has AA lining it

2 - the substrate binds (ES complex)

3 - additional bonds are formed to make the fit better (transition-state complex)

4 - products produced

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10
Q

Cofactors for enzymes are

A

Metal ions - which are INORGANIC

Small, non protein

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11
Q

Coenzymes for enzymes are

A

Prosthetic groups - tightly bound, does not dissociate away from enzyme

and co-substrates - associates with enzyme TEMPORARILY

They are ORGANIC

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12
Q

Cofactor examples

A

Mg, K, Ca, Zn, Fe, Cu

They are bond with enzyme molecule

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13
Q

Coenzymes examples

A

Vitamins!!!

NAD - B3/niacin
FAD - B2/riboflavin
Coenzyme A

Bind TEMPORARILY or permanently to enzyme NEAR active site

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14
Q

Water soluble vitamins are

A

Coenzymes

Thomas
Richard
Never
Pounded
PussySix
But
fondled
Chest

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15
Q

Enzymes need to be compartmentalized ___

A

Within the cell

Want to be in the ideal space for substrate + enzyme meeting

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16
Q

Enzymes have substrate specificity. Give 3 examples

A

Chymotrypsin has a hydrophobic active site for aromatic AA: trp, tyr, phen

Trypsin has a “-“ active site for “+” AA: lys, Arg

Elastase has a narrow active site for small uncharged AA: gly, ala, ser

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17
Q

What are the 3 types of enzymes

A

Isozymes

Allosteric enzymes

Proenzymes

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18
Q

Define isozyme

A

Multiple forms of an enzyme that catalyze the same reaction

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19
Q

Define allosteric enzymes

A

Multisubunit enzyme with identical or different polypeptide chains

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20
Q

Define proenzymes

A

biologically inactive substance which is metabolized into an enzyme

Zymogen -pancreas

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21
Q

What affects the activity of enzyme rxn and influence rate of rxn

A
  1. pH
  2. Temp
  3. Substrate conc/enzyme conc
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22
Q

What enzyme will activity will go up at acidic levels

A

Pepsin

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23
Q

what enzyme will go up at pH 7

A

Salivary amylase

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24
Q

What enzyme will go up at pH 9.5

A

Arginase

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25
Q

If temp is too low what happens to rate of enzyme activity

A

INACTIVE

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26
Q

If temp is too high what happens to rate of enzyme activity

A

Denatured

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27
Q

Which has a higher affinity for glucose hexokinase or glucokinase

A

HEXOKINASE

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28
Q

What would utilize hexokinase

A

Brain cuz it NEEDS glucose

29
Q

Where is glucokinase found

A

Liver
Parenchyma cells
Pancreatic islet cells

30
Q

What is the KM of hexokinase if we know it has a high affinity for glucose

A

0.1mM

This makes sure a supply of glucose for tissues is there even when the blood glucose is low

31
Q

What is the KM of glucokinase if we know it has a low aff for glucose

A

10mM
This is 100x less aff compared to hexokinase

32
Q

KM vs KD

A

KM = Michaelis constant
Kinetic constant
NOT equilibrium constant

Shows the affinity of substrates binding for the active site

KD = dissociation constant
thermodynamic constant
Equilibrium constant

Shows the affinity of the ligand towards an enzyme

33
Q

What changes enzymes rate (regulates)

A
  1. Substrates/inhibitors
  2. Allosteric regulation of enzymes
  3. Covalent modification of enzymes via hormonal reg
34
Q

Allosteric enzymes have _____ sites and _______. They show _______. And display ____ on a graph

A

Multiple active sites, change their conformation after they bind

Cooperative binding
Sigmoidal dependence

35
Q

Where does an allosteric enzyme that causes inhibition and activation bind

A

NOT at the active site

36
Q

___ are metabolic inhibitors or activators that affect activity of allosteric enzymes

A

Effectors

37
Q

Positive Effectors characteristics

A

Once it binds it changes both subunits to a higher affinity for

Shifts graph to the left

Activators bind more tightly to R state

38
Q

Negative effector characteristics

A

Binding both subunits to a low affinity form which inhibits activity

Bind more tightly to Tstate

39
Q

____ is a good example of allosteric effects

A

Hemoglobin

40
Q

Sigmoidal shape in allosteric curve is due to

A

Conformation change in enzyme

The cooperative binding

41
Q

What is a common way to quickly adjust activity of enzymatic reactions

A

Covalent modification

42
Q

Covalent modification is

A

Usually reversible
Phosphorylation
CAMP

43
Q

Adding or removing phosphate groups is an example of

A

Covalent modification

44
Q

Substrate availability results in _____ and take ______ long

A

Change in velocity

Seconds

45
Q

Product inhibition results in ____ and takes ____ long

A

Change in Vm and/or Km

Seconds

46
Q

Allosteric control results in _____ and takes _____ long

A

Change in Vm and/or Km

Seconds

47
Q

What kind of bond is allosteric control utilizing

A

Non-covalent

48
Q

Covalent modification results in ____ and takes ___ long

A

Change in Vm and/or Km

Seconds to minutes

49
Q

Induction or repression results in ____ and takes ____ long

A

CHANGE IN AMOUNT

Min to hrs to days

50
Q

Which regulator does not affect rate of reaction
Substrate availability
Allosteric control
Induction or repression
Covalent modification
Product inhibition

A

Induction or repression. It changes the amount of enzyme

51
Q

Allosteric control effects

A

End product

52
Q

Covalent modification affects

A

Another enzyme

53
Q

Induction or repression effects

A

Hormone/metabolite

54
Q

Induction or repression can alter

A

Protein sythesis

It takes a long time cuz its DNA and RNA

55
Q

_____ resemble the substrate and bind reversibly at the active site

A

Competitive inhibitors

56
Q

____ bind to the enzyme reversibly in a different domain than the active site changing the conformation of the enzyme

A

Non competitive inhibitors

57
Q

What does a comp. Inhibitor effect

A

Raises the KM
Because you need more substrate to fight for spots

Vmax stays the same

58
Q

What does a non competitive inhibitor effect

A

Lowers the vmax

KM stays the same
Cuz no one is interfering with the active site

59
Q

What does uncompetitive inhibition effect

A

BOTH Km and Vmax

60
Q

Lovastatin is an example of a _____ inhibitor. It effects the substrate ___

A

Competitive

HMG CoA

It decreases lipids

61
Q

____ is an example of a non competitive inhibitor to pyruvate kinase

A

Alanine

62
Q

Silver poisoning is an example of __

A

Non competitive inhibition

63
Q

Examples of uncompetitive inhibition

A

Inhibition of Arya sulphatase by hydrazine

Inhibition of intestinal alkaline phosphatase by phenylalanine

64
Q

What is the end result of a suicide inhibitor

A

Fewer enzyme molecules active to catalyze norm reactions - the vmax decreases

65
Q

Suicide inhibitors aka and what do they do

A

Irreversible

Bind Supa tight to ACTIVE SITE forming covalent bond and permanently inactivate enzyme

66
Q

Suicide inhibitors KM and VMAX effects

A

Vmax decreases
KM is unchanged

67
Q

Examples of suicide inhibitors

A

NSAID-Aspirin
Penicillin

68
Q

What kind of enzyme catalyzes irreversible metabolic reactions

A

Regulatory enzyme

69
Q

Example of allosteric regulatory enzyme

A

Phosphofructokinase

CBFM Final (18 decks)

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