enzymes

Question 1

what is an enzyme

Answer 1

globular protein

can be regulated reaction specificity

Question 2

what are ribozymes

Answer 2

have no protein but are catalytic RNA molecules

Question 3

what is a cofactor

usually what is it

Answer 3

non protein component needed for activity

CHANGES PROTEIN SHAPE

an ion of some sort

Question 4

what is a co enzyme

what are some examples

Answer 4

produced by vitamin take part in reaction
but don’t alter the shape of a enzyme

FAD, NAD+

Question 5

what is a prosthetic group

Answer 5

a co factor that doesn’t alter group but is attached closely and is needed to function

Question 6

all enzymes end in

Answer 6

-ase

Question 7

what do enzymes do

Answer 7

acceleration towards reaction equilibrium

lower the activation energy

Question 8

what is the best shape for an active site

Answer 8

the shape is complementary to the transition complex

lock and key is a load of bollocks

Question 9

how do enzymes reduce activation energy

Answer 9

desolvation - single out substrate from solution
induced fit
entropy reduction

Question 10

what happens if you add more substrate

Answer 10

a higher initial reaction rate and more product

Question 11

what is the initially reaction velocity called

Answer 11

V0

Question 12

when do you reach Vmax

Answer 12

when you have saturated all enzymes with substrate

Question 13

do you ever reach Vmax

Answer 13

not really

Question 14

what dose a larger Km indicate

Answer 14

a less stable enzyme substrate complex

Question 15

what dose a smaller Km value indicate

Answer 15

a more stable enzyme substrate complex

Question 16

what is Km

Answer 16

the substrate concentration to reach 1/2 Vmax

Question 17

so what dose
Vmax tell us
Km tell us

Answer 17

Vmax - fast - higher the better

Km - fit - the higher the number the less the affinity - faster

Question 18

what the two Isozymes that catalyse glucose + ATP = glucose-6-phospahte

Answer 18

glucokinase

hexokinase

Question 19

where is glucokinase located

Answer 19

in the liver

Question 20

where is the hexokinase located

Answer 20

everywhere else in the body

Question 21

what are the properties of glucokinase

Answer 21

high Km

high Vmax

Question 22

what are the properties of hexokinase

Answer 22

low Km

low Vmax

Question 23

what happens after you eat a meal and blood glucose goes up

Answer 23

hexokinase activity doesn’t respond however glucokinase responds PORPORTIONATLLY to blood glucose

Question 24

what happens when blood glucose is low

Answer 24

gluconeogenis realsease glucose from liver

but glucokinase cant phosphorolate the glucose due to its high Km

Question 25

what happens when glucose is phosphorylated

Answer 25

it is unable to cross a cell membrane

Question 26

when enzymes are in the blood tissue this is an indicator of

Answer 26

tissue damage

Question 27

how can you separate out proteins

Answer 27

electrophoresis

Question 28

what can electrophoresis separate proteins out by

Answer 28

charge or size

Question 29

the measurement of enzyme concentration or presence can help with making a...

Answer 29

diagnosis

Question 30

hexokinase has different Km values for which two sugars why the difference

Answer 30

glucose - low fructose - high main job is to phosphorylate glucose but can phosphorylate fructose if need be

Question 31

the catalysing of a reaction with two or more substrates usually involves...

Answer 31

the transfer of one group to another

Question 32

what dose lactate dehydrogenase exhibit

Answer 32

ordered sequential mechanisms

Question 33

what is ordered sequential mechanisms

Answer 33

``` into enzyme A then B then A out then B out ```

Question 34

what is a random sequential mechanism

Answer 34

enzyme binds A or B first then spits out A or B first RANDOM

Question 35

what are double displacement/ ping pong reactions

Answer 35

to create A + B = C + D A in = C out B in = D out

Question 36

what is an example of double displacement

Answer 36

transfer of amino acid from aspartate to alpha-ketoglutarate

Question 37

what are allosteric enzymes

Answer 37

enzymes which have other sites on them that can be regulated

Question 38

what is a good example of cooperative binding

Answer 38

haemoglobin

Question 39

what is cooperative binding

Answer 39

when the reaction velocity V0 increases after a substrate binds to one subunit - leading to increased affinity of the other sub units

Question 40

what is a competitive inhibitor

Answer 40

bind noncovalently to active site and have simillar shape to substrate will increase the Km and reduce the affinity

Question 41

what is a uncompetitive inhibitor

Answer 41

stops conformational change once enzyme and substrate have bound

Question 42

what is a non-competitive inhibitor

Answer 42

binds to a different 'allosteric site' causing a change in active shape

Question 43

what is the best shape for an inhibitor

Answer 43

something that looks like the transition state

Question 44

what is the concert model

Answer 44

when one molecule of substrate binds - it locks the other enzymes open

Question 45

what do allosteric actiuvators do

Answer 45

stabilise the ‘open’ conformation allowing S to bind more effectively

Question 46

what will allosteric inhibitors do

Answer 46

will stabilise the ‘closed’ conformation and make it difficult for S to bind

Question 47

what is the sequential model

Answer 47

after one substarte bids it opens its next door neighbour are that continues in SEQUENCE

Question 48

what is a proenzyme

Answer 48

Enzymes that exist as an inactive precursor protein

Question 49

how are the active enzymes formed from proproteins

Answer 49

the proprotein is cleaved by protease

Question 50

what is covalent modification

Answer 50

regulation by the covalent binding of a phosphorylation group

Question 51

what do Protein kinases do

Answer 51

add a phosphoryl group

Question 52

what do Protein phosphatases do

Answer 52

remove phosphoryl groups