Thursday 30 April 2020
Explain the factors that affect enzyme activity
Temperature; enzymes are protein in nature; and hence sensitive to
temperature changes; as temperature increases, enzyme activity also increases
until optimum/maximum; above this optimum the reaction decreases sharply; due
to the destruction of the enzyme structure/become denatured; making the enzyme
ineffective/non-functional; most enzymes have optimum temperature of between 35oC
and 40oC; when temperature decreases, the rate of enzyme reaction
decreases as the enzyme becomes inactivated; pH/acidity or alkalinity; most
enzymes have optimum pH of close to 7/neutral which is the intracellular pH;
however some enzymes work best in an alkaline medium while others work best
in an acidic medium/condition; as the pH
exceeds optimum, the enzyme activity decreases; extreme acidity or alkalinity
denatures most enzymes; Substrate concentration and enzyme concentration;
enzyme reaction increases with increase in substrate concentration; up to a
certain level where further increase in substrate concentration does not
increase the rate of enzyme reaction; this is because when substrate
concentration is increased, all the active sites of the enzyme are occupied;
however, when the enzyme molecules are increased, there is a proportional
increase in the maximum rate of enzyme action; enzymes are however required in
small amounts hence; they speed up the rate of biochemical reactions without
altering the equilibrium; Enzyme
cofactors/coenzymes; these are non-proteinous substances which activate the
enzymes; most enzymes will not work without them; examples of cofactors are
metallic ions such as iron, magnesium, zinc, copper and also vitamins as enzyme
coenzymes; these substances are required in small amounts and are used
repeatedly/can be recycled; Enzyme inhibitors; these are substances that
inhibit enzyme action by competing with the normal substrate for the active
sites; there are two types: competitive and non-competitive; competitive
inhibitors have no permanent effect on the enzyme action; while non-competitive
inhibitors combine permanently with the enzyme molecules thus distorting or
blocking the active sites permanently; examples of these inhibitors include
cyanides, mercury, silver; inhibition can be reduced by reducing the
concentration of the inhibitors; or by increasing the substrate concentration;
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