6.4: Enzymes speed up metabolic reactions by lowering energy barriers Flashcards
Why may a spontaneous reaction never happen?
A spontaneous reaction may never happen because of how slow the process will be, this is why an enzyme is needed
enzyme
a macromolecule that acts as a catalyst(mainly proteins here)
catalyst
a chemical agent that speeds up a reaction without being consumed by the reaction
What must a reactant molecule do in order to make new bonds
in order for a reactant molecule to make new bonds, it must first contort to a highly unstable state which is obtained through the reactant molecule absorbing energy from their surroundings
How does a molecule go back to its new stable state?
the molecule goes back to its original form by releasing its energy through heat
activation energy(EA)
the energy required to contort the reactant molecules so the bonds can break/change , the energy needed to push the reactant uphill(top of energy barrier) so that the downhill part can happen
transition state
the unstable state of a reactant after it had absorbed the surrounding thermal energy to get past the uphill and be able to break bonds
How does heat impact Enzymes reaction speed ?
heat can speed up reactions but it can also denature proteins and kill cells
catalysis
is used instead of heat, a catalyst/enzyme selectively(due to shape) speeding up a reaction, Enzymes Only changes the rate by lowering the activation energy needed(the barrier) so the reaction can happen better
substrate
the reactant and enzyme acts on
enzyme-substrate complex
when an enzyme binds to a substrate, soon forms a product(s)
active site
where only a certain area of the enzyme actually binds to the substrate
How often does the substrate attach to the enzyme
the enzyme is constantly changing shapes and only attaches to the substrate when the shape is right
induced fit
when the enzyme tightens around the bonded molecule
What holds the substrate to the active site ?
The substrate is held by the active site through weak interactions like hydrogen bonds and ionic bonds
enzyme mechanism
- enzyme changes to fit the reactant when they first attach
2. then the enzyme dissociates from reactants and restores shape
mechanisms for lowering FA
- enzymes template a way to react between 2 or more reactants
- distorting the substrate’s bonds makes EA need lower since the bonds are now easier to break
- the active site makes a sub environment for a certain reaction that is more conducive for that reaction, low pH for H+ transfer.
- amino acids in the activity site can covalently bond to the substrate and the side chain of an amino acid of the enzyme
How is efficiency of an enzyme impacted?
the efficiency of an enzyme is affected by environmental factors, such as temperature and pH, also affected by chemicals that influence enzymes which can also be used to our advantage(inhibitors)
optimal conditions(enzymes)
the right conditions for a certain enzyme
How does heat impact the efficiency of an enzyme ?
heat can increase the rate of collisions of substrates since molecules speed up, thermal energy can however agitate hydrogen bonds and ionic bonds that stabilize the shape of the enzyme
optimal temp for humans
35-40C(each enzyme has an optimal pH as well)
cofactors
personal nonprotein helpers for enzymes are inorganic(metals)
coenzyme
organic cofactor, vitamins, reaction will not happen without this if the enzyme requires coenzyme
competitive inhibitors
these inhibitors take the active site of the enzyme before the substrate, reversible and bond or not permanent
noncompetitive inhibitors
binds to a nonactive site region of the enzyme and changes the shape of the protein, nonreversible
