Enzymes

Question 1

what do enzymes do and what specifically do they not do

Answer 1

speed up the rate of reaction by stabilising the transition rate ie making it easier to get to. However, they don’t affect the shift in equilibrium

Question 2

what is an assay

Answer 2

a procedure for measuring biochemical/immunological activity of a sample

Question 3

What is michaelis constant

Answer 3

Km

Question 4

what does V = in enzymes

Answer 4

Vmax / 2

Question 5

define Km

Answer 5

it is the substrate conc at which the reaction rate is half its theoretical maximum value

Question 6

what happens to the Vmax and Km in competitive inhibition

Answer 6

Vmax is unchanged but Km is increased

Question 7

what happens to Vmax and Km in non - competition inhibition

Answer 7

Vmax is decreased (proportion of the enzyme is blocked off) and Km is unchanged

Question 8

what do NSAIDS do and what is the effect of it

Answer 8

inhibits COX-1, blocks prostaglandin release

Question 9

what is the mechanism of action of aspirin

Answer 9

there is covalent modification of serine residue in active site - competitive and irreversible

Question 10

what power does NADH and FADH2 have

Answer 10

they have reducing power as they carry elections

Question 11

which enzymes carries acyl units

Answer 11

Coenzyme A

Question 12

what do biotin and thiamine carry

Answer 12

CO2

Question 13

what do deficiencies in riboflavin (B2)
Niacin
Thiamine (B1)
Vitamin C
G6PD

Answer 13

ariboflavinosis (sores in the mouth)
pellagra - dementia, diahorrea and dermatitis
beriberi - effects heart and circulatory system
scurvy - fatigue depression
favism - causes haemolytic anaemia

Question 14

what is G6PD and what does the deficiency mechanism do

Answer 14

glucose 6 phosphate dehydrogenase - most common enzyme deficiency
x linked recessive (male) - produces large amounts of NADH

Question 15

what was the problem with primaquine

Answer 15

causes haemolytic crisis in people with G6PD deficiency

Question 16

what is 1 international unit

Answer 16

it is the amount of activity that will convert 1 micromole of substrate per minute under standard conditions

Question 17

enzymes catalyse the conversion of substrate to a product by

Answer 17

stabilising the transition state of the reaction

Question 18

enzyme activity in the body is controlled by…?

Answer 18

post translational medication of enzymes
expression of natural enzyme inhibitors
abundance of co factors such as metal ions

Question 19

what can enzymes be used to measure

Answer 19

blood glucose levels

Question 20

how is blood clotting mediated

Answer 20

by serine proteases

Question 21

organophosphorus compound such as novachik and sarin do what

Answer 21

have a similar mode of action to that of the insecticide malathion

Question 22

in what way do substrates bind to enzymes

Answer 22

via multiple weak interactions

Question 23

what is the michaelis mentor model

Answer 23

a model for measuring enzyme activity

Question 24

V(velocity) =

Answer 24

Vmax x [S]/[S] + Km

Question 25

on a graph how do you know where vmax and km are

Answer 25

v max is at the y axis and km is on the x axis

Question 26

how do you know if an enzyme is competition of non-comp via a graph

Answer 26

in comp they have the same v max

in non comp the v max changes

Question 27

what does a small km mean compared to a large one

Answer 27

small Km = high affinity

Question 28

what would happen to v max if you increased the amount of enzyme

Answer 28

it would increase

Question 29

what factors affect the rate of enzyme catalysed reactions

Answer 29

substrate conc
temperature
ph
inhibitors

Question 30

what does IC50 do and what is it

Answer 30

used to tell us the relative effectiveness of inhibitors - its the value of the inhibitor concentration at which 50% of activity remains

Question 31

why was primaquine bad

Answer 31

anti malarial drug which caused increased amounts of free radicals rbc becomes demanded and causes destruction

Question 32

what is a serpin

Answer 32

serine protease enzyme which act as an inhibitor of protease

Question 33

what is TPA

Answer 33

tissue type plasminogen activator - activates plasminogen to plasmin to destroy a blood clot

Question 34

what does trypsin do

Answer 34

cleaves chymotrypsinogen which helps in digestion

Question 35

what is an example of measuring isoenzymes

Answer 35

measure levels of creatine kinase after heart attack

Question 36

what would low blood albumin indicate

Answer 36

poor liver function

Question 37

what do the enzymes GPT and GOT indicate if in the blood serum

Answer 37

involved in amino acid metabolism and could indicate liver damage - GOT also found in muscle so may indicate something else

Question 38

what is used to remove from paracetamol poisoning

Answer 38

methionine a precise amount as toxic and must be given within 12 hours

Question 39

how would you measure paracetamol level in the blood

Answer 39

convert to aminophenol which reacts with orthodox-cresal in the presence of copper ions which create a coloured dye product

Question 40

how would you measure blood glucose

Answer 40

use metabolite specific enzyme - glucose that generates hydrogen peroxide byproduct - reacts with a dye

Question 41

what are asparaginases used for

Answer 41

in childhood acute lymphoblastic leukaemia - CALL - lowers asparagine levels to lower which affects growth of tumour cells

Question 42

what is one enzyme use in coronary thrombosis

Answer 42

thrombolytic agents such as TPA which is a serine protease which acts on fibrin clots

Question 43

name an enzyme as therapeutic agent

Answer 43

detoxifying agents - kidney dialysis breakdown of urea - use urase
converts urea into co2 and nh4 - ammonia absorbed back by activated charcoal - co2 expired through lungs