W6 Enzyme Action

Question 1

what is the enzyme transtion state theory

Answer 1

enzymes reduce activation barrier for smaller transition state energy

Question 2

what complex is formed when substrates bind to enzyme

Answer 2

ternary complex

Question 3

what are ping pong enzyme reactions

Answer 3

when 1 or more products bind before all substrate bind

Question 4

what are 4 methods of catalysis

Answer 4

by approximation
covalent
acid base
metal ion

Question 5

what is covalent catalysis

Answer 5

• temp binding of subtrate by nucleophlic attack
• intermediate lowers activation energy
• regenerate enzymes break covalent bond

Question 6

what are 3 examples of residues used for covalent catalysis

Answer 6

Lys
Asp
Cys

Question 7

what is acid base catalysis

Answer 7

• nucleophilic or electrophilci attack by acid or base
• donate/accept of protons stabilize the transition state

Question 8

which 2 acid/bases are used for catalysis

Answer 8

cystine
histidine

Question 9

what are the 3 most common metal ion catalyst

Answer 9

Fe2+
Zn2+
Cu2+

Question 10

how does phosphorylation regulate enzymes

Answer 10

adds 2 -ve charges and form 3+ H bonds for high energy transfer

Question 11

what do zymogens do

Answer 11

cleavage for activation of enzyme

Question 12

what is Ubiquitination of an enzyme

Answer 12

addition of ubiquitin to polypeptide
marks proteins for degradation

Question 13

what is an eample of ubiquitin

Answer 13

p27

Question 14

what do apoenzyme + cofactor make

Answer 14

holoenzyme

Question 15

what are 2 common co subtrates

Answer 15

ATP
NAD

Question 16

what are the 4 things that control amount of enzyme

Answer 16

transcription
translation
processing
stability

Question 17

what are 3 regulatory enzymes

Answer 17

heokinase
phosphofructokinase
pryuvate kinase

Question 18

what is activated for more Ca2+

Answer 18

CAMKs

Question 19

what do Ca2+ do for enzymes

Answer 19

increase affinity by binding to subtrate

Question 20

why is Compartmentalisation good for enzymes

Answer 20

allow simultaneous metabolic reactions and complexes

Question 21

what are uncompetitive inhibitors

Answer 21

bind to the ES complex instead of active sites

Question 22

what happens to Km when more comp inhibitors are added

Answer 22

increase Km

Question 23

what does more comp inhibitors mean for V max

Answer 23

nothing

Question 24

what does more non-comp do to V max

Answer 24

reduced

Question 25

what does more non-comp inhibitors mean for Km

Answer 25

nothing

Question 26

what does more uncomp inhibitors mean for V max and Km

Answer 26

reduced

Question 27

what do allosteric enzymes do

Answer 27

have other regulatory sites

Question 28

what type of kinetics does ATCase show

Answer 28

sigmoidal

Question 29

how are pyrimidine nucleotides synthesised

Answer 29

catalyse carbomoyl phosphate and asparate

Question 30

what does low CTP levels mean

Answer 30

high ATCase activity

Question 31

what does high CTP levels mean

Answer 31

low ATCase activity

Question 32

which subunit of ATcase reacts to CTP

Answer 32

r subunit

Question 33

what is the subunit of ATcase with 3 polypeptides

Answer 33

c subunit

Question 34

what is the subunit of ATcase with 2 polypeptides

Answer 34

r subunit

Question 35

where does PALA bind to inbihit ATcase

Answer 35

between pair of c chains

Question 36

how much are the r and c subunits moved when PALA binds

Answer 36

c = 12 Å apart + 10° rotation r = 15° rotation

Question 37

in what state do subtrate bind more efficiently to

Answer 37

R state

Question 38

how does CTP inhibit enzyme

Answer 38

stabilised T state

Question 39

what is ATP known as allosterically

Answer 39

allosteric activator

Question 40

what is CTP known as allosterically

Answer 40

allosteric inhibitor

Question 41

what type of regulation do allowsteric enzymes show

Answer 41

cooperative regulation

Question 42

which protein is regulated by compartmentalisation

Answer 42

preprotrein

Question 43

what is porphyria

Answer 43

build up of porphyrins

Question 44

when is erythropoietic protoporyphyria triggered

Answer 44

exposure to UV

Question 45

what does a mutation of ferrochelatase do

Answer 45

catalyses protoporphyrin and Fe2+

Question 46

how is heme B produced

Answer 46

bent porphyrin forms transition state since allows for enzymes binds more easily

Question 48

what is N-methylmesoporphyrin do

Answer 48

generate antibodies to catalyse ferrochelatase reaction

Question 49

what does ferrochelatase help do

Answer 49

bend porphyrin

Question 50

what does hexokinase do

Answer 50

induce gene expression for glucose metabolism

Question 51

4 factors that induce HKII gene expression

Answer 51

insulin cold hypoxia exercise

Question 52

what does ubiquitination do to blood pressure

Answer 52

raises blood pressure

Question 54

What are serine proteases inhibited by

Answer 54

Serpins

Question 55

What does fructose 2,6 bisphosphate regulate

Answer 55

Glycolysis

Question 56

What genetics does all steric enzymes not show

Answer 56

Michaelis-menton

Question 57

What binds to inhibit prosphofructokinase

Answer 57

ATP and citrate

Question 58

What is chymotrysinogen

Answer 58

Zymogen of chymotrypsin Found in pancreas

Question 59

What is chymotrysinogen activated by

Answer 59

Trypsin