Enzyme I and Enzyme regulation II blood clotting (Allostery and regulation)

Question 1

Aspartate (ATCase)

Answer 1

Homotrophic effector, an enzyme that catalyzes the first step in pyrimidine biosynthesis. CTP is the end product.

Question 2

Metabolism

Answer 2

Biochemical reactions in cells.

Question 3

Allosterism

Answer 3

A means of controlling enzymes by binding of a small molecule to an enzyme- controls the enzymes activity (not an on/off switch but more like volume control.)

Question 4

Effector

Answer 4

A molecule that binds to an enzyme

Question 5

Covalent modification

Answer 5

controlling an enzyme by making or breaking covalent bonds. (ex peptide bonds breaking usually activates an enzyme)

Question 6

Control of synthesis of an enzyme

Answer 6

Like an “on/off switch”. Enzyme is not made in the cell if it is not needed, Ex. enzyme that makes glucose in cells that don’t produce glucose (skin cells).

Question 7

Substrate availability

Answer 7

Enzyme will not be active without a substrate available.

Question 8

Substrate

Answer 8

A molecule on which an enzyme acts, bonds to the active site.

Question 9

Homotropic allosteric modulator

Answer 9

A substrate as well as a regulatory molecule for an enzyme’s activity. Typically an activator of an enzyme.

Question 10

Heterotropic allosteric modulator

Answer 10

A regulatory molecule that is NOT also the enzymes substrate.

Question 11

Homotropic effector

Answer 11

Allosteric interactions that occur when several of the same molecules are bound to the protein. ex. the binding of aspartate to ATCase.

Question 12

Heterotropic effector

Answer 12

Allosteric interactions that occur when different substances are bound to the protein. ex inhibition of ATCase by CTP and activation by ATP.

Question 13

Fibrin

Answer 13

Protein that forms polymers that forms clot.

Question 14

Fibrinogin

Answer 14

Converted to fibrin by protein called Thrombin

Question 15

Thrombin

Answer 15

A serine protease, key to amplification phase.

Question 16

Serine protease

Answer 16

Serine proteases are enzymes that cleave peptide bonds in proteins

Question 17

Cellular Response step 1

Answer 17

Epithelial tissue is damaged exposing collagen.

Question 18

Cellular Response step 2

Answer 18

Platelets bind to collagen, binds to surface receptors.

Question 19

Cellular Response step 3

Answer 19

Platelet integrins get activated and bind tightly to extracellular matrix to anchor to site of wound.

Question 20

Cellular Response step 4

Answer 20

Von Willebrand factor forms additional links between platelets glycoproteins and the fibrils of the collagen

Question 21

Cellular Response step 5

Answer 21

Amplification process begins with the release of platelet factor that inhibits heparin (anti-cloting factor) and thromboxine is released (makes the platelets stick together)

Question 22

Cellular Response step 6

Answer 22

Calcium released from intercellular stores.

Question 23

Molecular response

Answer 23

Occurs after cellular response, consists of 2 phases (initiation phase and amplification phase)

Question 24

Intrinsic pathways

Answer 24

contact activation pathway, serine proteases activate other serine proteases (amplification). Prothrombin - thrombin - fibrinogen - fibrin.

Question 25

extrinsic path

Answer 25

Tissue factor pathways (more important)

Question 26

Initiation phase step 1

Answer 26

tissue damage stimulates complex formation

Question 27

Initiation phase step 2

Answer 27

Complex activates Factor 10 (FX), platelet membrane phospholipids and calcium inefficiently convert FX to FXa.

Question 28

Initiation phase step 3

Answer 28

FXa, Ca, and other factors inefficiently convert prothrombin to a tiny amount of thrombin.

Question 29

Initiation phase step 4

Answer 29

Thrombin is key for amplification.

Question 30

Amplification Phase step 1

Answer 30

FVIII Normally bound to Von Willebrand factor in a complex and is inactivate until it is released by action of thrombin

Question 31

Amplification Phase step 2

Answer 31

FXIa helps favor production of more FIXa

Question 32

Amplification Phase step 3

Answer 32

FIXa plus FVIII stimulates production of a considerable amount of FXa

Question 33

Amplification Phase step 4

Answer 33

FVa joins FXa and Ca to make a much larger amount of Thrombin.

Question 34

Hemophilia

Answer 34

clotting disorder, patient does not clot.

Question 35

Vitamin K

Answer 35

Fat soluble vitamin that facilitates calcium binding that is necessary for clotting.

Question 36

Warfarin (Coumadin)

Answer 36

Inhibits Vit K epoxide - reduces clotting factors.

Question 37

Four common types of enzyme regulation

Answer 37

Allosterism, Covalent modification, Control of Synthesis, and Availability of substrate.

Question 38

When is the hyperbolic V0 vs (S) plot converted from a hyperbolic shape to a sigmoidal shape?

Answer 38

When substrates acts as allosteric effectors.

Question 39

Feedback inhibition

Answer 39

The end product of a metabolic pathway inhibits the first enzyme in the pathway. Mediated allosterically. (once the end product had been produced in enough abundance it binds to the enzyme, prevents too much from being created.

Question 40

Zygomens

Answer 40

Enzymes that are synthesized in an inactive form whose activation requires covalent modification. ex digestive enzymes, their enzymatic activity may be harmful to the tissue where they are made.

Question 41

Trypsin

Answer 41

Primary activator of entire class of proteolytic enzymes. Improper activation of trypsin in or too close to the pancreas can lead to pancreatitis which arises when the proteases attack proteins in the pancreas.

Question 42

Zymogens activation by a protease cascade

Answer 42

Allows the body to activate enormous amounts of enzymes very rapidly. It is useful for activating proteases for digestion and for controlling blood clotting