Enzymes Flashcards
What is a catalyst?
a catalyst speeds up the rate of a reaction without being consumed itself in the reaction
What is an enzyme?
an enzyme is a protein and a catalyst
What is an example of an enzyme in the body?
carbonic anhydrase
- speeds up the reaction of water with carbon dioxide to remove carbon dioxide
- is a metalloenyzme = metal is Zinc 2+
What are the four ways an enzyme can work?
binding the substrates
binding other molecules - cofactors (reagent in a lab)
doing the reaction
releasing the product
Why are enzymes specific?
an enzymes will only catalyse specific types of reactions using specific substrates
- recognition and catalytic abilities of enzymes only appears through specific interactions with the functional groups in an active site
What are esterase enzymes?
enzymes found in the bloodstream
- hydrolyses any drug containing an ester
have the ability to bind a wide range of substrates
How do esterase enzymes work?
the enzyme binds the substrate and a molecules of water
the enzyme active site has both acidic and basic groups - esterase
acidic group protonates the carbonyl group of the ester
basic group deprotonates the water molecule
nucleophilic attack by the OH group of the carbonyl carbon reforms the carbonyl group of the active site
loss of the OR group of the ester as an alcohol
What are the types of metal contains enzymes?
metal activated enzymes
- are associated loosely with ions
- typically from group 1 or 2
metalloenzymes
- contain tightly bound metals
- typically from the transition metals block
What is the function of metalloenzymes?
bind substrates in specific orientations
- carry out redox reactions
- change in metal oxidation state
- stabilise negative charges
What are the three ways an enzyme can regulate drugs action?
act as a drug target
activate prodrugs
can start drug metabolism
What is an enzyme inhibitor?
molecules that can bind in the enzyme and prevent substrates and cofactors from binding
- reaction would not be catalysed or take place
What is the difference between reversible and irreversible inhibitors?
reversible inhibitor
- competes with the substrate for the active site = binds in a similar way
- activity is concentration dependent = can overcome inhibition by increasing substrate concentration, activity is only reduced
irreversible inhibitor
- binds irreversibly to the active site, often with a covalent bond
- activity is concentration independent.
What is an alternative site that inhibitors can bind to on the enzyme?
inhibitor can bind at the allosteric site
- site other than the active site
- binding changes the shape of the active site so substrate cannot bind
What is competitive and non-competitive inhibition?
competitive
- reversible = compete for binding site
- reversible = allosteric binding, inhibitor can be removed
non-competitive
- irreversible = inhibitor does not come off and substrate cannot bind
What is a prodrug?
a biologically inactive compound which can be metabolized in the body to produce a drug
