Are specific for what they catalyze and do not permanently change during reactions End in the word ase Function of Enzymes Enzymes work by lowering the activation energy the amount of energy needed to start a reaction ID: 655146
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Slide1
EnzymesSlide2
Enzymes are…
Proteins that act as catalysts (accelerate reactions) by creating a new reaction pathway
Are specific for what they catalyze and do not permanently change during reactionsEnd in the word -aseSlide3
Function of Enzymes
Enzymes work by lowering the activation energy (the amount of energy needed to start a reaction). Slide4
Check for Understanding
With your partner, label the products, reactants, activation energy, progress of reaction, and free energy on the image below. Question: Using this image, what is one thing that the enzyme does in this reaction?Slide5
Enzyme-Substrate Complex
Substrate is the substance an enzyme acts on and is specific for each enzyme
Active site is the region of the enzyme that binds to the substrate
Enzyme
Substrate
Active SiteSlide6
Lock-and-Keys Model
Enzyme may be used again
Enzyme-substrate complex
E
S
P
E
E
P
Reaction coordinateSlide7
Lock-and-Keys Model
Keys = Substrates (multiple can bind to each enzyme)
Lock = Active Site on the EnzymeAs a result of the reaction, the products change shapeAfter the reaction is complete, the substrates are released, freeing up the enzymes to bind with more substrateSlide8
Check for Understanding
With your partner, using what we just discussed, fill in the boxes on the diagram below. Include the name of the part of the enzyme or substrate, and the events that are taking place for the boxes labeled #1-4.Slide9
Active Site
Enzyme
Substrate matching the enzyme approaches the active site
The substrate bonds to the active site forming the enzyme-substrate complex
Product
Product
The products formed are released and the enzyme is free to bind to a new substrate
The enzyme speeds up the reaction, changing the shape of the substrateSlide10
Induced Fit
10
A
change
in the
configuration
of an
enzyme’s active site
(H+ and ionic bonds are involved).
Induced
by the
substrate.
Enzyme
Active Site
substrate
induced fitSlide11
Factors that Impact Enzyme Function
Temperature
pHSubstrate Concentration InhibitorsSlide12
Temperature
Enzymes move faster as temperature increases
Above optimum temperature, the enzyme denatures – preventing it from binding with the substrate
Temperature / °C
Enzyme
activity
0
10
20
30
40
50
DenaturationSlide13
pH
Extreme pH will result in denaturation
Enzyme structure changesSubstrate will no longer fitpH levels different for different enzymes
Optimum pH values
Enzyme activity
Trypsin
Pepsin
pH
1
3
5
7
9
11Slide14
Substrate Concentration
More substrate causes the substrate to use up the available enzyme faster
Once all of the enzyme is bound, the reaction will slow and move at a constant stateSlide15
Competitive Inhibitors
Chemicals that resemble an enzyme’s normal substrate and compete with it for the active site
Enzyme
SubstrateSlide16
Noncompetitive Inhibitors
Chemicals that bind to part of the enzyme (not the active site), resulting in changing the shape of the active site
prevents the substrate from binding
Enzyme
active site
altered
Noncompetitive
Inhibitor
Substrate