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Biochemistry Exam 2 > Enzyme Regulation > Flashcards

Enzyme Regulation Flashcards

1
Q

What 4 things are metabolic enzymes are regulated by?

A

Compartmentalization- different locations

Enzyme Concentration- on/off switch

Enzyme Activity- volume control

Hormone Signals and Second Messengers- master regulators

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2
Q

Substrate level control acts on a _____ ______

A

Single reaction

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3
Q

Feedback control targets a _____ ____ __ ____ _______

A

different step in the pathway

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4
Q

Activators ______ more products

A

promote

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5
Q

Inhibitors _____ more products

A

prevent

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6
Q

Isozymes _____ ____ _____ subunits

A

Mix and Match

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7
Q

What do isozymes do?

A

They catalyze the same reaction but with different efficiencies

Tissue Specificity: Compartmentalized isozymes

Development: Temporal expression of isozymes

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8
Q

What do reversible covalent modifications do?

A

They add 1 or more functional group s to inactivate/activate the enzyme

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9
Q

For reversible covalent modifications, post-translational modifications create _________ amino acid

A

nonproteinogenic- amino acids that are not normally encoded or found in the genetic code

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10
Q

What are the 8 common covalent modifications of protein activity and their donor molecule?

A

PAM FAGS U

Phosphorylation- ATP

Acetylation- Acetyl CoA

Myrisoylation- Myrisoyl CoA

ADP ribosylation- NAD+

Farnesylation- Farnesyl Pyrophosphate

gamma-Carboxylation- Bicarbonate ion

Sulfation- 3’-Phosphoadenosine- 5’-Phosphosulfate

Ubiquination- Ubiquitin

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11
Q

What are the examples of modified proteins for each of the 8 common covalent modifications?

A

Phosphorylation- Glycogen phosphorylase

Acetylation- Histones

Myrisoylation- Src

ADP ribosylation- RNA polymerase

Farnesylation- Ras

gamma-Carboxylation- Thrombin

Sulfation- Fibrinogen

Ubiquination- Cyclin

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12
Q

What are the protein functions for each of the 8 common covalent modifications?

A

Phosphorylation- Glucose homeostasis, energy transduction

Acetylation- DNA packing, transcription

Myrisoylation- Signal Transduction

ADP ribosylation- Transcription

Farnesylation- Signal transduction

gamma-Carboxylation- Blood clotting

Sulfation- Blood clot formation

Ubiquination-Control of cell cycle

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13
Q

What are the 5 categories of molecules each reversible covalent modifications can be found in?

What do carbohydrates provide to the cell?

A

Lipids- Myristic Acid and Farnesyl

Nucleic Acids- ADP ribose

Proteins- Ubiquitin

Carbohydrates- The greatest source of diversity to the proteome

Small molecules- gamma carboxylation, Sulfation, Acetylation, Methylation

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14
Q

What 4 things does phosphorylation affect?

A
  1. Thermodynamics- ATP hydrolysis can drive unfavorable reactions
  2. Kinetics- Physiological processes dictate reaction time
  3. Cell processes- ATP amounts dictated by metabolism (energy charge); Signal transduction amplification (catalytic turnover)
  4. Shape and Charge Complementary- each phosphate adds (-2) charge and possible (3+) H-bonds
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15
Q

Kinases verses phosphatases

A

Kinases add phosphates Phosphatases remove phosphates *Note that the name of the phosphate indicates which amino acid the phosphate will be added to

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16
Q

Where does allosteric binding NOT occur?

A

At the active site!

17
Q

What are the 2 types of Allostery?

A

Heteroallostery: Effector binds at the allosteric site. The regulation of allosteric enzymes by a molecule other than the substrate. Homoallostery: Substrate induced regulation of allosteric enzymes. These enzymes are invariably multisubunit proteins, with multiple active sites.

18
Q

An inhibitor will ___ the rate of product formation An activator will ___ the rate of product formation

A

Inhibit- Decrease Activator- Increase

19
Q

ATCase is inhibited by what?

Aspartate Carbamoyltransferase (ATCase)

A

CTP

20
Q

Binding of CTP prefers the _______

A

T/inactive state

21
Q

Binding of ATP prefers the _______

A

R/active state

22
Q

Protein synthesis regulation= on/off switch. What are the two levels of control that are possible?

A

Transcription regulation at the promoters

Translation regulation at the UTRs

23
Q

What controls Transcription?

A

Histones

24
Q

Histone Acetylation ______ Transcription

A

Promotes

25
Q

Histone Phosphorylation ______ Transcription

A

Prevents

26
Q

Histone Methylarion either _____ or ____ Transcription

A

Promotes or Prevents

27
Q

What 2 things control Translation?

A

miRNAs and UTRs *remember that mRNA levels do not correlate to protein levels

28
Q

How do we carry out irreversible covalent modification?

A

Proteolytic activation

29
Q

In what 4 important molecules do we see proteolytic activation alter enzymes from zymogens to their active state?

A

Proteases:

  • Digestive enzymes
  • Collagenase (development)
  • Caspases (apoptosis)

Collagen

Blood clotting factors

Insulin/Hormones

30
Q

For the proteolytic activation of chymotrypsin, what converts chymotrypsinogen to chymotrypsin in the primary structure?

A

Trypsin- cuts chymotrypsinogen in 4 spots to make 3 chains

31
Q

Draw out the proteolytic cascade

A

Find this picture on the last slide of this lecture.

Biochemistry Exam 2 (13 decks)

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