2.5 Flashcards
what is the active site
the special area on the enzyme were the actual catalytic reaction takes place
what is the interaction between the substrate and active site like
very specific
only one type of substrate fits into the active site
enzyme-substrate specificity
what is the active site a result of
the folding of the polypeptide chain, resulting in a 3d shape formed b the polypeptide chain frost the active site where the substrate interacts with the enzyme.
what happens when the substrate enters the enzymes active site
the enzyme changes shape slightly, induced fit results in tighter binding of the substrate to the active site
what are enzymes
biological catalyst, globular proteins that can speed up a biochemical reaction
what is the induced fit model
suggests that when the substrate enters the active site, it triggers a change in the three dimensional shape of the enzyme that allows a tighter fit, called an induced fit. this is possible because of the flexibility of the protein molecules that make up thhe enzyme
when they fit together tightly, the enzyme induces the weakening of bonds within the molecules of the substrate, thus reducing the activation energy needed for the reaction.
what theory did the induced fit model replace
the lock and key theory
what did the lock and key hypothesis
enzyme functions as a lock while the substrate functions as a key, there is a perfect match
the induced fit model suggests that a substrate is capable of inducing a change
there are three steps of the induced fit model
attraction - substrate enters the enzyme
reaction - substrate enzyme complex, conformational change
release - products of the reaction are released, enzyme reverts to original shape
what is the active site
the sequence of amino acids responsible for the catalytic activity of enzymes
what is activation energy
the minimum energy required that reacting particles should possess in order for a reaction to occur
how do enzymes affect the activation energy
the activation energy is lowered
what is a catalytic reaction
when an enzyme converts the substance into products such as when amylase hydrolyses starch to produce di and monosaccharides
what does enzyme catalysis involve
molecular motion and collision of substrates
what is an exothermic or exergonic reaction
a reaction where product formation is associated with release of energy
what is an endothermic/endergonic reaction
a reaction where product formation is associated with absorption of energy
what factors can affect the catalytic properties of enzymes
temperature, pH, substrate concentration and enzyme concentration
how does temperature affect enzymes
low - enzymes move slowly, low chance of collision
optimum temp - rate of enzymatic reaction is the highest
too high - enzyme can denature
graph - slow increase, peak, rapid decrease straight line down
how does substrate concentration affect enzymes
low - more enzymes than substrate, rate of reaction is low
increasing - more substrates, more chances of collision, enzymatic reaction rises gradually
increase is halted when all active sites are occupied by substrate molecules after this point, adding more substrate does not affect the rate of reaction.Vmax
how does pH affect enzymes
enzymes have their own optimum pH which differs, extreme values can denature an enzyme by altering the three dimensional structure of its active site however, if the pH is just a little lower of higher than the optimal, the rate of reaction gradually decreases
when is denaturing irreversible
in extreme conditions, such as in eggs, usually it is reversible
what does denaturation do to an enzyme
it destroys the tertiary or quaternary conformation of a protein. when the temperature is high enough or the pH is extreme, the secondary structure of a protein can be altered
what happens If the change in temperature and pH is only minor
some proteins may still be reversible
different uses of industrial enzymes
industry
environment
agriculture
