What Is The Effect Of Temperature On Enzyme Activity?

Temperature can affect a lot of different factors hence its effect on enzyme activity is very complex. It affects the speeds of molecules, the activation energy of the catalytic reaction and the thermal stability of the enzyme and substrate.

At low temperatures (say at around 0 centigrade) the rate of enzyme reaction is very slow. The molecules have low kinetic energy and collisions between them are less frequent and even if they do collide the molecules do not posses the minimum activation energy required for the reaction to occur. It can be said that the enzymes are deactivated at low temperatures.

An increase in temperature increases the enzyme activity since the molecules now possess greater kinetic energy. The rate of enzyme activity is highest between 0-40 centigrade and this increase is almost linear.

After 40 the rate of reaction starts to decrease. This is because the increase in temperature after 40 does not increase the kinetic energy of the enzyme but instead disrupts the forces maintaining the shape of the molecule. The enzyme molecules are gradually denatured causing the shape of the active site to change. Temperatures above 65 centigrade completely denature the enzymes.

There are some enzymes known as 'extremophiles' found in thermophillic organisms. They retain activity at 80 centigrade.

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