Enzymes

Question 1

Enzyme defintion

Answer 1

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

Question 2

Enzyme binds ______ to substrate

Answer 2

Reversibly

Question 3

Enzyme substrate complex ______forms _______

Answer 3

Irreversibly
Product
Regenerates catalyst

Question 4

Active sites contain

Answer 4

Catalytic residues

Question 5

Specifiticty of enzymes involve what forces

Answer 5

Van der Waals
Electrostatic
H-bonding
Hydrophobic interactions

Question 6

Enzyme mechanismm

Answer 6

Facilitates formation of transition state

Question 7

Cofactors

Answer 7

Small molecules bound to enzyme

Question 8

Enzyme with/without cofactor

Answer 8

Without - apoenzyme (inactive)

With - holoenzyme (active)

Question 9

Two groups of cofactors

Answer 9

Metal ions and small organic molecules

Question 10

Coenzymes

Answer 10

Small organic cofactors

Question 11

Prosthetic groups

Answer 11

Coenzymes tightly bound

Question 12

_____ are often precursors to coenzymes

Answer 12

Vitamins

Question 13

V

Answer 13

Number of moles formed per second

Question 14

Km

Answer 14

Concentration of S that is 1/2 of Vmax

Question 15

Km measures

Answer 15

How tightly substrate binds

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

Question 16

V relationship to Vmax and Km

Answer 16

Proportional to Vmax

Inversely proportionalto Km

Question 17

Line-weaver Burke improtant points

Answer 17

X-intercept = 1/-Km
Y-intercept = 1/Vmax
Slope = Km/Vmax

Question 18

Reversible inhibition types

Answer 18

Competitive and noncompetitive

Question 19

Competitve inhibiton

Answer 19

Binds active site
Overcome with more substrate
Changes Km

Question 20

Noncompetitive inhibition

Answer 20

Binds other site
Cannot be overcome with substrate
Changes Vmax

Question 21

Irreversible inhibtion typically

Answer 21

Involves covalently bound

Can bind anywhere

Question 22

Kinase

Answer 22

Transfer of phosphate using ATP

Question 23

Phoshorylase

Answer 23

Adds inorganic phosphate to substrate iwhtout ATP

Question 24

Phosphatase

Answer 24

Removes phosphatre

Question 25

Dehydrogenase

Answer 25

Redox

Question 26

Hydroxylase

Answer 26

Add hydroxyl

Question 27

Carboxylase

Answer 27

Transfers CO2

Question 28

Mutase

Answer 28

Relocates functional group within a molecule

Question 29

Feedbakc inhibition

Answer 29

Product regulates earlier enzyme | Common in metabolism

Question 30

Allosteric and how is it different than noncompetitive

Answer 30

Has allosteric sites that can be activated or inhibited | Sigmoidal M-M kinetics

Question 31

Isozymes and example

Answer 31

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

Question 32

H form and M form of lactate dehydrogenase

Answer 32

H - Heart (higher affinity) | M - skeletal (lower)

Question 33

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

Answer 33

Reversible - phosphorylation, acetylation | Irreversible - attachment of lipid group that localizes protein to a membrane

Question 34

Autoinhibition and example

Answer 34

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

Question 35

Mechnaism of autoinhibition

Answer 35

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

Question 36

Zymogens

Answer 36

Inactive precursors | Most undergo proteolytic cleavage to become active

Question 37

Types of zymogens

Answer 37

Digestive enzymes Blood clotting Collagenase Capsases

Question 38

Aspirin common name and goup

Answer 38

Acetylsalicylic acid | NSAID

Question 39

NSAID mechanism

Answer 39

Inhibit COX (cyclooxygenase enzymes)

Question 40

Isoforms of COX

Answer 40

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

Question 41

Aspirin targets which forms of COX?

Answer 41

Bot h

Question 42

COX enzyme reaction

Answer 42

Turn arachidonic acid into PGG2...eventually forms prostaglandins and thromboxane

Question 43

Prostaglandins

Answer 43

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

Question 44

Aspirin...reversible or irreversible?

Answer 44

Irreversible...adds acetyl group

Question 45

Aspirin reaction with Cox 1 and COx 2

Answer 45

Ser530 COX 1 | Ser 516 Cox 2

Question 46

Other NSAIDs bind to COX enzymes

Answer 46

Competitively and reversibly

Question 47

Statins

Answer 47

Competitive inhibitors of HMG-CoA reductase | Reduce cholesterol synthesis

Question 48

HMG-CoA reductase reaction and what it requires

Answer 48

HMG-CoA to mevalonic acid | 2 NADPH

Question 49

HMG-CoA reductase location and catalytic domain

Answer 49

Membrane protein | Cat. domain - cytosol

Question 50

Statin mechanism

Answer 50

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