2.7 Factors affecting enzyme action

Learning Objectives

• Learn how the rate of an enzyme controlled reaction is measured.

• Learn how temperature affects the rate of an enzyme controlled reaction.

• Learn how pH affects the rate of an enzyme controlled reaction.

• Learn how substrate concentration affects the rate of reaction.

How to measure the progress of enzyme-catalysed reactions...

• Generally, one of two ‘outcomes’ are measured over time:

- the formation of the products of the reaction.- the disappearance of the substrate.

Draw and explain the following graphs...Vo

lum

e of

oxy

gen

prod

uced

Time

Mas

s of s

tarc

h

Time

Enzyme-catalysed reaction in which oxygen is formed due to the

action of catalase on hydrogen peroxide.

Enzyme-catalysed reaction in which starch disappears due to the

reaction of amylase.

The Effect of Temperature on the Rate of an Enzyme-Controlled Reaction

The Effect Of pH

The Effect Of pH on the Rate of an Enzyme-Controlled Reaction

The Effect Of Changing Substrate Concentration

The effect of changing the amount of substrate on the rate of an enzyme-controlled reaction. As the amount of substrate increases from 0 to B, the rate of reaction increases. As the amount of substrate increases from B to C, the rate of

reaction does not increase any further.