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Biochemistry 1 > Enzyme Regulation (Quiz 2) > Flashcards

Enzyme Regulation (Quiz 2) Flashcards

1
Q

What are enzymes?

A

-proteins
-biological catalysts
-they accelerate specific chemical reactions
-some enzymes require molecules other than proteins for the enzymatic activity

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2
Q

What is a holoenzyme/haloenzyme?

A

-the active enzyme
-enzyme with nonprotein
-usually vitamins or minerals
-they’re essential for enzymatic activity
-ex: dehydrogenase with NAD

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3
Q

What is an apoenzyme?

A

-inactive enzyme
-its inactive bc it doesn’t have its nonprotein component, so if it gets its nonprotein component then it becomes activated and is now called a holoenzyme
-ex: dehydrogenase

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4
Q

What are cofactors?

A

-component of holoenzyme
-non-protein metal ion such as Cu, Mg, Zn

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5
Q

What are coenzymes?

A

-holoenzyme
-non-protein component is a vitamin (organic molecules)
-active form of vitamin

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6
Q

What are cosubstrates?

A

coenzymes that only transiently associate with the enzyme

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7
Q

What are prosthetic groups?

A

coenzyme (made of vitamin + protein) that is permanently associated with the enzyme

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8
Q

An active compound formed by a carboxylase + biocytin =

A

a holoenzyme

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9
Q

Which vitamin is associated with the coenzyme flavin adenine dinucleotide (FAD)?

A

riboflavin (vitamin B2)

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10
Q

Which vitamin is associated with the coenzyme nicotinamide adenine dinucleotide (NAD)?

A

nicotinic acid (also known as niacin or vitamin B3)

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11
Q

Which vitamin is associated with the coenzyme, Coenzyme A?

A

pantothenic acid, also known as pantothenate or vitamin B5

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12
Q

Which vitamin is associated with the coenzyme pyridoxal phosphate (PLP)?

A

pyridoxine (vitamin B6)

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13
Q

Which vitamin is associated with the coenzyme thiamine pyrophosphate (TPP)?

A

thiamin (vitamin B1)

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14
Q

Which vitamin is associated with the coenzyme biocytin?

A

biotin (vitamin B7)

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15
Q

Which vitamin is associated with the coenzyme tetrahydrofolate?

A

folic acid (vitamin B9)

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16
Q

Which enzymes are regulated?

A

only rate limiting enzymes

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17
Q

What are the 4 types of enzyme regulation mechanisms (cells don’t want to waste time and energy, so the enzyme needs to be regulated)?

A

1) allosteric regulation
2) covalent modification
3) activation by proteolytic cleavage
4) isozymes

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18
Q

In many pathways, the end product is an allosteric inhibitor of the first enzyme. This is called _________________ regulation

A

negative feedback

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19
Q

What is allosteric regulation?

A

-allosteric regulation binds to a site other than the active site and changes enzyme confirmation, which results in an apparent change in binding affinity
-the allosteric site that bonded will cause change in the active site so that the substrate cant bind to the active site
-its reversible binding of modulators to sites other than the active site

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20
Q

______ shape curve indicates a regulated enzyme

A

S

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21
Q

Does allosteric regulation have Km and Vmax?

A

no

22
Q

Increased 2,3 BPG is an example of an allosteric __________

A

inhibitor

23
Q

Presence of CO is an example of an allosteric _____________

A

activator

24
Q

What is covalent modification?

A

-most common form of covalent modification is phosphorylation
-ser, thr, and tyr all have OH in their R group, so they can be phosphorylated (OH is replaced with phosphate)
-this is reversible and phosphate can go back to OH when needed
-hormones frequently do this, like insulin and glucagon to turn on and off enzymes

25
Q

What is activation by proteolytic cleavage?

A
26
Q

What are some examples of zymogens (type of inactive form of enzyme)?

A
27
Q

What are isozymes?

A

-used for enzyme regulation
-groups of enzymes catalyze the same reaction but differ in AA sequence and enzyme properties
-example: Glut 1 and 2 are isozymes

28
Q

What are the 6 classes of enzymes?

A

1) oxidoreductase
2) transferase
3) hydrolase
4) lyase
5) isomerase
6) ligase

29
Q

Which enzymes are a part of the oxidoreductase enzyme class?

A

-oxidase (removes H/electrons)
-reductase (adds H/electrons)
-dehydrogenase (removes or adds H)

30
Q

What type of reaction is catalyzed with oxidoreductase?

A

transfer of electrons or H atoms

31
Q

Which enzymes are a part of the transferases enzyme class?

A

-kinase (adds phosphate)
-phosphorylase (breaks polymer and adds phosphate to one of the monomers)
-transferase

32
Q

What type of reaction is catalyzed with transferases?

A

group transfer reactions

33
Q

What 2 groups of enzymes are a part of the hydrolase enzyme class?

A

1) digestive enzymes
2) phosphatase (removes phosphate)

note: both use water in hydrolysis reaction to break bond

34
Q

What type of reaction is catalyzed with hydrolases?

A

hydrolysis reactions (use water to break polymer into monomers)

35
Q

Which enzymes are a part of the lyases enzyme class?

A

-decarboxylase (removes carbon)
-lyases

36
Q

What type of reaction is catalyzed with lyases?

A

breaking of various chemical bonds by means other than hydrolysis and oxidation

37
Q

Which enzymes are a part of the isomerases enzyme class?

A

-mutase (name is same)
-isomerase (isomers are molecules with the same formula but different structure)

38
Q

What type of reaction is catalyzed by isomerases?

A

isomerization

39
Q

Which enzymes are a part of the ligase enzyme class?

A

-synthase (ATP not seen directly in rxn)
-synthetase (ATP seen directly)
-carboxylase (adds carbon)

40
Q

What do ligases do?

A

join 2 molecules with covalent bonds usually coupled with ATP hydrolysis

41
Q

What does oxidase do?

A

removes H or electrons

42
Q

What does reductase do?

A

adds H or electrons

43
Q

What does dehydrogenase do?

A

removes or adds hydrogen

44
Q

What do kinases do?

A

add phosphate

45
Q

What does phosphorylase do?

A

breaks polymer and adds phosphate to one of the monomers

46
Q

What does phosphatase do?

A

removes phosphate and uses water for hydrolysis reaction

47
Q

What does decarboxylase do?

A

remove carbon

48
Q

What do synthases do?

A

used in reactions without ATP directly present to glue molecules together

49
Q

What do synthetases do?

A

used in reactions with ATP directly present to glue molecules together

50
Q

The enzyme trypsin is classified as which of the following?
A) oxidoreductase
B) lyase
C) hydrolase
D) ligase

A

C) hydrolase

51
Q

What does the inhibitor bind to during feedback inhibition?

A

allosteric site of the enzyme being inhibited

Biochemistry 1 (12 decks)

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