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My Packs: (WIZEPREP) (BIOCHEM 2280) > Chapter 4: 4.3 Enzymes > Flashcards

Chapter 4: 4.3 Enzymes Flashcards

1
Q

State:

Function of enzymes

A

Drastically increases rates of reactions, allowing cellular function (and more specifically, metabolism) to occur

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2
Q

Enzymes are highly specific in their ———- (even showing ——————)

A
  • Substrates
  • Stereo-specificity
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3
Q

How do enzymes increase reaction rate?

A

Stabilization of the transition state (lowering the energy)

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4
Q

True or False:

Each enzyme has a specific substrate and active site

A

True

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5
Q

How many classes of enzymes are there?

A

6

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6
Q

List:

The 6 classes of enzymes

A
  1. Oxidoreductases
  2. Transferases
  3. Hydrolases
  4. Lyases
  5. Isomerases
  6. Ligases
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7
Q

State:

Function of oxidoreductases

A

Catalyzes oxidation-reduction reactions

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8
Q

What are names of oxidoreductases?

A

Oxidases, dehydrogenases, reductases

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9
Q

What happens in an oxidation-reduction reaction?

A
  • One substrate is oxidized (loses electrons)
  • One substrate is reduced (gains electrons)
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10
Q

In redox reactions:

What is the method to keep track of where electrons are going?

A

Follow the hydrogen atoms, typically:
* Oxidized molecules lose hydrogen atoms
* Reduced molecules gain hydrogen atoms

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11
Q

State:

Function of transferases

A

Group transfer reactions

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12
Q
  1. What are kinases?
  2. What is the process that they perform called?
A
  1. Transfer phosphate groups
  2. Phosphorylation
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13
Q

State:

Function of hydrolases

A

Catalyzes hydrolysis reactions

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14
Q

What is a hydrolysis reaction?

A

Breaking apart molecules with water

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15
Q

True or False:

Hydrolases are the largest group of enzymes

A

True

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16
Q

What enzymes are included in the hydrolase group? (4)

A
  • Proteases
  • Lipases
  • Nucleases
  • Esterases
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17
Q

State:

Function of lyases

A

Addition of groups to double bonds or removal of groups to form double bonds

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18
Q

What are lyases also referred to as?

A

Synthases (perform addition reactions)

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19
Q

Give a WIZEPREP example of a(n):

  1. Oxidoreductase
  2. Transferase
  3. Hydrolase
  4. Lyase
  5. Isomerase
  6. Ligase
A
  1. Xanthine dehydrogenase
  2. Transketolase
  3. Phloretin hydrolase
  4. Methylisocitrate lyase
  5. Isopentenyl pyrophosphate isomerase
  6. Synthetase
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20
Q

State:

Function of isomerases

A

Transfer groups within molecules (create isomers)

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21
Q

What enzyme type is found in the isomerase group?

A

Mutases

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22
Q

State:

Function of ligases

A

Joins two molecules through the use of ATP (energy source)

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23
Q

Define:

Enzyme Active Site

A

A pocket on the enzyme that provides a specific environment, within which a reaction can occur more rapidly

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24
Q

List:

Levels of specificity of an enzyme active site

A
  1. High degree of specificity
  2. Function group specificity
  3. Broader specificity
25
Q

Explain:

High degree of specificity (Enzyme active site)

A

Only acts properly on only one substrate

26
Q

Explain:

Functional group specificity (Enzyme active site)

A

Acts on multiple substrates with a key functional group

27
Q

Explain:

Broader specificity (Enzyme active site)

A

Acts on substrates with the same molecular “scaffold”

28
Q

What is the “lock and key” in an enzyme?

A
  • Lock: Shape of active site
  • Key: Substrate

The shape of the active site is complementary to the substrate

29
Q

True or False:

The enzyme cannot change shape to accept a substrate

A

False, it is its own microenvironment and can change to accept a substrate

30
Q

Define:

Nucleophiles

A

Electron rich species that have an affinity for positively charged (nucleus)

31
Q

Define:

Electrophiles

A

Electron poor species that have an affinity for electron rich atoms

32
Q

Describe:

Nucleophilic substitution

A
  1. Electron-rich chemical species (nucleophile) replaces functional group
  2. The nucleophile replaces an electrophile and leaving the functional group (known as the substrate)
33
Q

Define:

Proximity Effect

A

Brings components close together, increasing the chance of completing the reaction

34
Q

Transition states are ——— and ——–

A
  1. Fleeting
  2. Unstable
35
Q

How is stabilization of transition state achieved?

A

The enzyme binds to the transition state and stabilizes it

36
Q

Describe:

Acid-Base Catalysis

A

Electrons are either transferred from an acid catalyst to the substrate or from the substrate to a base catalyst

37
Q

State the role of the functional group for:

Aspartate

A

Cation binding; proton transfer

38
Q

State the role of the functional group for:

Glutamate

A

Cation binding; proton transfer

39
Q

State the role of the functional group for:

Histidine

A

Proton transfer

40
Q

State the role of the functional group for:

Cysteine

A

Covalent binding of acyl groups

41
Q

State the role of the functional group for:

Tyrosine

A

H-bonding to ligands

42
Q

State the role of the functional group for:

Lysine

A

Anion binding; proton transfer

43
Q

State the role of the functional group for:

Arginine

A

Anion binding

44
Q

State the role of the functional group for:

Serine

A

Covalent binding of acyl groups

45
Q

What can cofactors be?

A
  1. Essential Ions
  2. Coenzymes
46
Q

For essential ion cofactors:

What are essential ions?

A

Mg2+, Ca2+, Fe2+, Co+

47
Q

For essential ion cofactors:

What are the two types?

A
  1. Activator ions: Closely bound
  2. Metal ions: Tightly bound
48
Q

For coenzyme cofactors:

What are coenzymes?

A

Organic compounds

49
Q

For coenzyme cofactors:

What are the two types?

A
  1. Cosubstrates: Loosely bound
  2. Prosthetic groups: Tightly bound
50
Q

What is NAD+?

A

Nicotinamide Adenine Dinucleotide
* Coenzyme
* Reduced form is NADH

51
Q

What is NADP+?

A

Nicotinamide Adenine Dinucleotide Phosphate
* Coenzyme
* Reduced form is NADPH

52
Q

What is FAD2+?

A

Flavin Adenine Dinucleotide
* Coenzyme
* Reduced form is FADH2

53
Q

What is ATP?

A

Adenosine triphosphate
* Coenzyme

54
Q

List:

Forms of Enzyme Regulation

A
  1. Substrate Availability
  2. Covalent Modifications
  3. Allosteric Control
  4. Zymogens, Proenzymes
55
Q

How does Substrate Availability regulates enzymes?

A

Enzyme can only catalyze reaction if there is substrate present to act on

56
Q

How do Covalent Modifications regulate enzymes?

A

Enzyme induced chemical changes to enzymes that can activate or de-activate enzymes

57
Q

How does Allosteric Control regulate enzymes?

A

A regulatory molecule binds to a site on the enzyme, separate form the active site, and alters enzyme shape and function
* Feedback inhibition

58
Q

What are Zymogens and Proenzymes?

A

Inactive precursors of enzymes

59
Q

Give an example of zymogens/proenzymes

A

Digestive enzymes (activate when expelled from cell)
* Trypsinogen to trypsin
* Proelastase to elastase
* Chymotrypsinogen to Chymotrypsin
* Etc.

My Packs: (WIZEPREP) (BIOCHEM 2280) (32 decks)

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