Enzymes Flashcards
what do enzymes do and what specifically do they not do
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
what is an assay
a procedure for measuring biochemical/immunological activity of a sample
What is michaelis constant
Km
what does V = in enzymes
Vmax / 2
define Km
it is the substrate conc at which the reaction rate is half its theoretical maximum value
what happens to the Vmax and Km in competitive inhibition
Vmax is unchanged but Km is increased
what happens to Vmax and Km in non - competition inhibition
Vmax is decreased (proportion of the enzyme is blocked off) and Km is unchanged
what do NSAIDS do and what is the effect of it
inhibits COX-1, blocks prostaglandin release
what is the mechanism of action of aspirin
there is covalent modification of serine residue in active site - competitive and irreversible
what power does NADH and FADH2 have
they have reducing power as they carry elections
which enzymes carries acyl units
Coenzyme A
what do biotin and thiamine carry
CO2
what do deficiencies in riboflavin (B2) Niacin Thiamine (B1) Vitamin C G6PD
ariboflavinosis (sores in the mouth)
pellagra - dementia, diahorrea and dermatitis
beriberi - effects heart and circulatory system
scurvy - fatigue depression
favism - causes haemolytic anaemia
what is G6PD and what does the deficiency mechanism do
glucose 6 phosphate dehydrogenase - most common enzyme deficiency
x linked recessive (male) - produces large amounts of NADH
what was the problem with primaquine
causes haemolytic crisis in people with G6PD deficiency
what is 1 international unit
it is the amount of activity that will convert 1 micromole of substrate per minute under standard conditions
enzymes catalyse the conversion of substrate to a product by
stabilising the transition state of the reaction
enzyme activity in the body is controlled by…?
post translational medication of enzymes
expression of natural enzyme inhibitors
abundance of co factors such as metal ions
what can enzymes be used to measure
blood glucose levels
how is blood clotting mediated
by serine proteases
organophosphorus compound such as novachik and sarin do what
have a similar mode of action to that of the insecticide malathion
in what way do substrates bind to enzymes
via multiple weak interactions
what is the michaelis mentor model
a model for measuring enzyme activity
V(velocity) =
Vmax x [S]/[S] + Km
on a graph how do you know where vmax and km are
v max is at the y axis and km is on the x axis
how do you know if an enzyme is competition of non-comp via a graph
in comp they have the same v max
in non comp the v max changes
what does a small km mean compared to a large one
small Km = high affinity
what would happen to v max if you increased the amount of enzyme
it would increase
what factors affect the rate of enzyme catalysed reactions
substrate conc
temperature
ph
inhibitors
what does IC50 do and what is it
used to tell us the relative effectiveness of inhibitors - its the value of the inhibitor concentration at which 50% of activity remains
why was primaquine bad
anti malarial drug which caused increased amounts of free radicals rbc becomes demanded and causes destruction
what is a serpin
serine protease enzyme which act as an inhibitor of protease
what is TPA
tissue type plasminogen activator - activates plasminogen to plasmin to destroy a blood clot
what does trypsin do
cleaves chymotrypsinogen which helps in digestion
what is an example of measuring isoenzymes
measure levels of creatine kinase after heart attack
what would low blood albumin indicate
poor liver function
what do the enzymes GPT and GOT indicate if in the blood serum
involved in amino acid metabolism and could indicate liver damage - GOT also found in muscle so may indicate something else
what is used to remove from paracetamol poisoning
methionine a precise amount as toxic and must be given within 12 hours
how would you measure paracetamol level in the blood
convert to aminophenol which reacts with orthodox-cresal in the presence of copper ions which create a coloured dye product
how would you measure blood glucose
use metabolite specific enzyme - glucose that generates hydrogen peroxide byproduct - reacts with a dye
what are asparaginases used for
in childhood acute lymphoblastic leukaemia - CALL - lowers asparagine levels to lower which affects growth of tumour cells
what is one enzyme use in coronary thrombosis
thrombolytic agents such as TPA which is a serine protease which acts on fibrin clots
name an enzyme as therapeutic agent
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
