A Catalyst increases the rate of reaction by providing alternative energy pathway ; usually increasing the rate of by 1012-1020. However it does not affect free energy ∆G (can’t make endergonic reaction go). Instead an enzyme can couple an exergonic reaction with an endergonic reaction via ATP breakdown.
It will decrease EAfor a spontaneous reaction and make it proceed faster
Often needed for molecules with HIGH KINETIC STABILITY (HIGH ENERGY BARRIER)
Rate is proportional to # of molecules you can activate; therefore reduce EA. More molecules can be activated therefore increasing rate of reaction.
Why do we need catalyst enzymes?
Catalyst enzymes make reaction proceed faster with having to wait a long duration of time and without a significant increase in temperature.
Tertiary Structure (very flexible; bigger than substrate)
Two theories of thought on how substrate active site– with enzyme wrapping around it
INDUCED FIT: Initiates bonds between substrate and enzyme are weak; enzymes chances conformation upon binding to strength binding
LOCK & KEY: The active site of enzyme is a rigid/ specific active site; however this fails to explain stabilization of transition state.
**Substrate must be in the transition state to be catalyzed
There is usually MUCH more substrate than enzyme and shift the reaction to the right
An increase of temperature can lead to potentially more molecules reaching the EA
How do Enzymes lower EA?
Orient substrate properly; makes substrate collide & react
Change interaction, exposing it to alternative charge (ionic reaction)
Changing shape of substrate molecule (forcing it into transition state)
NOTE: Enyzmes do these things to increase probability of substrate reaching EA.
St. Rosemary Educational Institution. "How does Enzyme Catalysis Work." http://schoolworkhelper.net/. St. Rosemary Educational Institution, Last Update: 2015. Web. Retrieved on: Friday 27th November 2015. http://schoolworkhelper.net/how-does-enzyme-catalysis-work/.