Enzymes Flashcards
enzyme
globular protein that catalyses specific metabolic reactions
lock and key hypothesis
-complimentary to each-other
-substrate and enzyme have kinetic energy so they move around
-by chance some substrates collide with an active site in such a way that they fit together
model of action of lock and key theory
random movement brings substrate to active site
enzyme-substrate complex is formed
interaction
enzyme-product complex is formed
product leaves the enzyme
enzyme is unchanged and ready to bind
induced fit hypothesis
the enzyme can change shape slightly as the substrate molecule enters to ensure a perfect fit and increase the efficiency of the catalysis
progress of an enzyme-catalysed reaction
initial rate is high
rate gets lower as less substrate molecules are available
rate of product formation or substrate disappearance
effect of temperature
low: low kinetic energy, successful enzyme-substrate collision is less likely, low rate.
high: high kinetic energy, energetic vibrations, hydrogen bonds broken, shape changed, enzyme denatured
effect of enzyme concentration
as enzyme concentration increases so will the rate of reaction until it reaches saturation
effect of substrate concentration
as substrate concentration increases the rate of reaction will also increase until it reaches saturation
competitive inhibitor
similar shape to substrate and binds to enzyme’s active site
Non- competitive inhibitor
binds to enzyme’s allosteric site, induces a conformational change so active site changes shape
control metabolic reactions in end-product inhibition negative feedback loops
Enzyme protein structure
Tertiary
Catabolic
Breaks down
Anabolic
Join together
