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ENZYME 2 (Factors affecting enzyme activity) - Coggle Diagram
ENZYME 2
(Factors affecting enzyme activity)
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TEMPERATURE
Bell shaped Curve
As temperature increases, enzyme activity increases until a peak in enzyme activity which called (
Optimum temperature
)
In human the optimum temperature is around (35C to 40C), any further increase in temperature leads to a decrease in enzyme activity due to the denaturation of the enzyme protein. (Denaturation can be irreversible in extreme situations.)
Thermophilic Bacteria (e.g. Thermus aquaticus) have Optimum Temperature of 70C
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PH
Bell shaped curve
Each enzyme has an Optimum PH but also has a working range of PH values
At very acidic and alkaline PH values denaturation of enzyme occurs which is the breaking of molecular bonds within the protein when those bonds are broken, the shape of the enzyme changes, and it's no longer fit to its specific substrate
For example:
PEPSINE
is maximally active at PH=2, where other enzymes which are designed to work at natural PH are denatured by such an acidic environment.
SUBSTRATE CONCENTRATION
(Most Enzymes follow Michaelis-Menten Kinetics in which the curve is hyperbolic. in contrast, allosteric enzymes do not follow Michaelis-Menten, and their curve is sigmoidal.)
Enzymes activity will increase when there is plenty of substrate. (As the concentration of the substrate increases, the rate of enzyme activity increases.) However, the rate of enzyme activity does not increase forever because a point will be reached when the enzymes become
saturated
. (It calls Maximal velocity or Vmax)
Michaelis-Menten equation is an equation describes the relationship between initial reaction velocity and substrate concentration.
Michaelis-Menten equation-characteristics & importance of Km
Km (Michaelis constant) equals the substrate concentration at which the initial reaction velocity is ½ Vmax.
Km does not vary with the enzyme concentration.
Km is characteristic of an enzyme and its particular substrate
It used to determine the mechanism of action of enzyme inhibitors
It reflects the affinity of an enzyme for its substrate (Small Km: high affinity, Large Km: low affinity)
Compare between different enzymes
Measure the catalytic efficiency of an enzyme is the Kcat/Km ratio
Michaelis-Menten equation Assumption
Substrate concentration is much greater than enzyme concentration
Enzyme-substrate concentration doesn't change with time
Initial velocity is only used in analysis of E reactions
