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Foundations Test 1 > Enzymes > Flashcards

Enzymes Flashcards

1
Q

Enzyme defintion

A

Substance that increases rate of reaction but stays same as it was b4

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2
Q

Enzyme binds ______ to substrate

A

Reversibly

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3
Q

Enzyme substrate complex ______forms _______

A

Irreversibly
Product
Regenerates catalyst

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4
Q

Active sites contain

A

Catalytic residues

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5
Q

Specifiticty of enzymes involve what forces

A

Van der Waals
Electrostatic
H-bonding
Hydrophobic interactions

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6
Q

Enzyme mechanismm

A

Facilitates formation of transition state

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7
Q

Cofactors

A

Small molecules bound to enzyme

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8
Q

Enzyme with/without cofactor

A

Without - apoenzyme (inactive)

With - holoenzyme (active)

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9
Q

Two groups of cofactors

A

Metal ions and small organic molecules

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10
Q

Coenzymes

A

Small organic cofactors

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11
Q

Prosthetic groups

A

Coenzymes tightly bound

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12
Q

_____ are often precursors to coenzymes

A

Vitamins

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13
Q

V

A

Number of moles formed per second

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14
Q

Km

A

Concentration of S that is 1/2 of Vmax

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15
Q

Km measures

A

How tightly substrate binds

Lower Km = more tightly bound = more likely to form product

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16
Q

V relationship to Vmax and Km

A

Proportional to Vmax

Inversely proportionalto Km

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17
Q

Line-weaver Burke improtant points

A 
X-intercept = 1/-Km
Y-intercept = 1/Vmax
Slope = Km/Vmax
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18
Q

Reversible inhibition types

A

Competitive and noncompetitive

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19
Q

Competitve inhibiton

A

Binds active site
Overcome with more substrate
Changes Km

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20
Q

Noncompetitive inhibition

A

Binds other site
Cannot be overcome with substrate
Changes Vmax

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21
Q

Irreversible inhibtion typically

A

Involves covalently bound

Can bind anywhere

22
Q

Kinase

A

Transfer of phosphate using ATP

23
Q

Phoshorylase

A

Adds inorganic phosphate to substrate iwhtout ATP

24
Q

Phosphatase

A

Removes phosphatre

25
Q

Dehydrogenase

A

Redox

26
Q

Hydroxylase

A

Add hydroxyl

27
Q

Carboxylase

A

Transfers CO2

28
Q

Mutase

A

Relocates functional group within a molecule

29
Q

Feedbakc inhibition

A

Product regulates earlier enzyme

Common in metabolism

30
Q

Allosteric and how is it different than noncompetitive

A

Has allosteric sites that can be activated or inhibited

Sigmoidal M-M kinetics

31
Q

Isozymes and example

A

Differ in sequence but catalyze same reaction
Allows fine-tuning
Lactate dehydrogenase

32
Q

H form and M form of lactate dehydrogenase

A

H - Heart (higher affinity)

M - skeletal (lower)

33
Q

Covalent modification (which are reversible and which are not?)

A

Reversible - phosphorylation, acetylation

Irreversible - attachment of lipid group that localizes protein to a membrane

34
Q

Autoinhibition and example

A

Portion of enzyme keeps it inactive by regulatory subunits until activator binds
Protein Kinase A

35
Q

Mechnaism of autoinhibition

A

Regulatory has pseudosubstrate sequence that binds active site of catalytic units…activator binds to regulatory sequence

36
Q

Zymogens

A

Inactive precursors

Most undergo proteolytic cleavage to become active

37
Q

Types of zymogens

A

Digestive enzymes
Blood clotting
Collagenase
Capsases

38
Q

Aspirin common name and goup

A

Acetylsalicylic acid

NSAID

39
Q

NSAID mechanism

A

Inhibit COX (cyclooxygenase enzymes)

40
Q

Isoforms of COX

A

COX 1 and COX 2 (means it is an isoenzyme)

41
Q

Aspirin targets which forms of COX?

A

Bot h

42
Q

COX enzyme reaction

A

Turn arachidonic acid into PGG2…eventually forms prostaglandins and thromboxane

43
Q

Prostaglandins

A

Make neurons more sensitive
Dilate or constrict vessels
Prevent or promotoe platelet aggregation

44
Q

Aspirin…reversible or irreversible?

A

Irreversible…adds acetyl group

45
Q

Aspirin reaction with Cox 1 and COx 2

A

Ser530 COX 1

Ser 516 Cox 2

46
Q

Other NSAIDs bind to COX enzymes

A

Competitively and reversibly

47
Q

Statins

A

Competitive inhibitors of HMG-CoA reductase

Reduce cholesterol synthesis

48
Q

HMG-CoA reductase reaction and what it requires

A

HMG-CoA to mevalonic acid

2 NADPH

49
Q

HMG-CoA reductase location and catalytic domain

A

Membrane protein

Cat. domain - cytosol

50
Q

Statin mechanism

A

Binds to active site of HMG-CoA reductase and excludes HMG-CoA

Foundations Test 1 (15 decks)

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