06 Enzymes
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Transcript of 06 Enzymes
ENZYMES
Enzymes
Most, but not all end in the suffix …ase Participate in reactions but are not used up or
changed in any way …although they can eventually “wear out” Can perform either catabolic (destructive)
reactions. eg. 1 substrate = 2 products Can perform either anabolic (constructive)
reactions. eg. 2 substrate = 1 products
Some quick facts.Enzymes …
Act at both the intra and extracellular level Act on SUBSTRATE and yield PRODUCT Reduce the ACTIVATION energy required to
start a reaction in the body Are very specific, each individual type of
substrate is acted upon by a specific enzyme Generally names are based on the specific
substrate (eg lipids acted upon by lipase)
Enzyme Structure
Enzymes have an active site and a regulatory region The active site is where substrate binds to the enzyme The regulatory region is where cofactors coenzymes or enzyme
inhibitors can alter the function of an enzyme
Substrate
Active site
Regulatory region
Products
Enzyme inhibitor
Enzymes – inhibitors / cofactors
Enzyme inhibitors can be either competitive or non-competitive
A competitive inhibitor blocks the substrate from entering the active site
A non-competitive inhibitor binds to the regulatory region, thereby changing the shape of the active site
Other enzymes will not work unless a particular cofactor occupies the regulatory region
The “Lock and Key” model of enzyme activity
The enzyme provides a perfect fit for a particular substrate
The “Induced Fit” model of enzyme activity
The substrate induces the enzyme to change shape to create a tighter fit
Factors Affecting Enzyme Activity
pH Most biological enzymes operate
at a neutral pH range of 6-8 If enzymes are at a pH outside
their optimum range, their shape will change and they will be less efficient.
Enzyme
Cells
Carbonic Anhydrase
Trypsin Pepsin
Location Blood Small Intestine
Stomach
Opt. pH 7.6 7.4 8.0 2.0
Factors Affecting Enzyme Activity
Temperature Most biological enzymes have an optimum
temperature of 37° If an enzyme is exposed to temperatures higher than
optimum, it will permanently denature. If an enzyme is exposed to temperatures lower than
optimum, it will become inactive until temperature returns to optimum.
The enzymes of other organisms have optimum temperatures suited to the environment in which they live
Effect of temperature
Factors Affecting Enzyme Activity
Enzyme Concentration An increase in enzyme conc. will cause an
increase in reaction rate but won’t increase the yield.
Substrate concentration Reaction rate will initially increase as
unoccupied enzymes take on substrate but will then plateau.
Inhibition Other molecules can block the active site or
regulatory region of an enzyme.
Increasing substrate concentration
Enzymes – advanced content
Biochemical pathways Inhibition of biochemical pathways Allosteric enzymes Biochemical processes