Enzymes Flashcards
What type of proteins are enzymes?
Globular proteins
What does a biological catalyst do?
Lowers activation energy to speed up a reaction.
What is the lock and key process?
-An enzyme substrate complex is formed.
-The substrate is held in place by the active site.
-The products of the reaction leave the active site .
-The enzyme is never destroyed (repeated process).
What does the lock and key process state?
The active site is fixed and exactly complementary to the substrate it binds to.
What does the induced theory state?
The enzyme changes shape for a closer fit between the active site and substrate.
What is the induced fit process?
-The enzyme changes its shape for a closer fit to the substrate.
-This causes a conformational change, changing the tertiary structure of the protein.
-The active site can then form an enzyme substrate complex.
-Between the enzyme and substrate is weak bonds.
-The bonds place stress of the substrate.
-The bonds are then broken and the products are formed.
-Still not a permeant change.
What does induced theory explain?
How actiavtion energy is lowered to speed up a process.
How is activation energy lowered?
-The weak bonds which put stress on the substrate are easily broken and don’t need much energy to break so can lower activation energy.
What are intercellar enzymes?
-Act within cells
-Many different types.
What are extra cellar enzymes?
-Act externally to the cells.
-Single cell organisms release enzymes into their immediate environment.
-Many multi-cellar organisms release enzymes into body cavities and organs.
What are the 4 factors which effect enzyme activity?
PH, temperature, substrate concentration and enzyme concentration.
What does denature mean?
The bonds holding the tertiary structure of the protein begin to break, the active site changes shape and the substrate is no longer complementary.
What does optimum mean?
The conditions at which a reaction with an enzyme is at its quickest rate.
Explain the temperature enzyme graph.
-Temperature increases and so does enzyme activity as there is more collisions between the substrate and enzymes as they gain kinetic energy.
-At optimum temperature there is the fastest rate of enzyme activity.
-Then the enzyme denatures so activity decreases as the active site is no longer complemntry.
Explain the PH enzyme graph.
-Enzyme starts off denatured as the PH is too low to from any ESC.
-At its optimum PH is the only time it can form ESC and also its fastest rate of activity.
-Then the enzyme denatures again as the PH is then too high and the active site is no longer complementary.
Why can enzyme substrate complex’s only form at the optimum PH?
-AT the optimum PH is the perfect concentration of H+ ions (PH is changed by the concentration of H+ ions).
-As the concentration changes the active site is changed.
-The ions react with the polar and charged groups changing the interaction as it breaks hydrogen and ionic bonds so the substrate is no longer complementary.
Explain the substrate concentration graph.
-Increase in substrate increases enzyme activity as there are more collisions between the enzyme and substrate.
-Then the graph plateaus as there is no more active sites available for the substrate to bond to.
-As more substrates are added now the rate of reaction will still not increase.
Explain the enzyme concentration graph.
-Increases at first as there are more complex’s formed as the enzyme is the limiting factor.
-The graph then plateaus as the active sites have binded to a substrate and the enzyme is no longer the limiting factor but something else is such as substrate concentration.
-Graph would increase if substrate concentration was also increased.
What does a competitive inhibitor do?
-Binds directly to the active site forming an enzyme-inhibitor complex.
What is an example of a completive inhibitor?
Carbon Monoxide.
How does a completive inhibitor work?
-Decreases rate of reaction as substrate cannot bind to the active site anymore (no longer complementary).
-Does not denature an enzyme
How can we go against competitive inhibitors?
By increasing substrate concentration
-Increases the chance of the substate binding to the active site not the inhibitor.
What does a non-competitive inhibitor do?
-Binds somewhere else on the the enzyme and changes the structure so the active site is no longer complementary.
How does a non-competitive inhibitor work?
-Changes the tertiary structure the shape of the active site changes.
-Slows down rate of reaction.
Explain a graph with a non-competitive inhibitor present.
-Has no effect on the rate of reaction at first (slowly increases).
-The has a plateau as no enzymes are left (some binded to substrate some inhibitor).
-Adding more substrate does not effect the rate of reaction as the inhibitor changes the active site
Explain the graph with a competitive inhibitor present.
-No effect on rate of reaction at first.
-Still then increases as substrate is added but at a slower rate as some enzymes are still binding to the active site
-Plateaus when no more enzymes are available to form a complex.
How are enzymes present in the rate of a metabolic reaction?
-Enzyme activity is highly controlled to keep the metabolic system at a constant rate.
How are inhibitors involved in the metabolic system?
-The final product of a a metabolic pathway acts as a non-competitive inhibitor to one of the enzymes earlier along the train.
-The metabolic pathway therefore controls itself since the product gets produced, the more inhibitors in the pathway the slower it will be.
-It is easily reversed when the the body is not producing enough.
