Factors Affecting Enzyme Action

Enzymes are globular proteins which reduces the Activation enzegy(the minimum amount of energy required to initiate a reaction) and speed up of a biochemical reactions.

In previous blogs we have studied about the structure and different models of reaction mechanism of enzyme action now we will study about the factors which effect the activity of enzymes .

The factors that affect enzyme activity are given below;

1-TEMPERATURE

2-PH

3-ENZYMES CONCENTRATION

4-SUBSTRATE CONCENTRATION

The way in which they affect the rate of enzyme action are discussed below:

1-TEMPERATURE:

It is define as *The degree of hotness or coldness of a body*.

Actually temperature is the average kinetic energy of molecules.

Heating increases the molecular motion due to which substrate and enzymes move quickly getting high kinetic energy which help them in acheving Activation energy and in this way the probability of reaction increases.

For every 10 degree centigrade increase in temperature doubles the rate of reaction but their is a limit of temperature to which rate of reaction increase this limit is called optimum temperature.

The temperature at which enzymes work best is called OPTIMUM TEMPERATURE.

If the temperature increases from optimum level the rate of reaction not increases but the enzymes denature means enzymes destroyed completely.

The optimum temperature is different for different organisms enzymes FOR EXAMPLE:

The optimum temperature for mammalian enzymes is 37 degree centigrade but some bacterial enzymes has optimum temperature of 70+ Degree centigrade.

IMPORTANT POINTS:

If the temperature is reduced to freezing point the enzymes become inactive not denature means they can be restored.

The temperature at which inactive enzymes become active is called MINIMUM TEMPERATURE.

2-PH:

The PH at which enzymes work best is called OPTIMUM PH.

For most enzymes optimum PH is 7-8 but some enzymes work best at extreme PH like protease present in animals stomach work best at 1 PH .

As we know the enzymes are globular protein and at active site amino acids(positive and negative) are present when we change the pH the charge on aminoacids at active site changes as a result substrate and enzymes repel each other and they no longer bind and no reaction occurs.

Some enzymes with their optimum pH are given below:

LIPASE (PANCREAS) 8.0

LIPASE (STOMACH) 4.0-5.0

LIPASE (CASTOR OIL) 4.7

PEPSIN 1.5-1.6(2)

TRYPSIN 7.8-8.7

UREASE 7.0

INVERTASE 4.5

MALTASE 6.1-6.8

AMYLASE (PANCREAS) 6.7-7.0

AMYLASE (MALT) 4.6-5.2

CATALASE 7.0

The factor which effect the enzyme activity the most is pH.

3- ENZYMES CONCENTRATION:

As the enzymes concentration increases the rate of reaction increases linearly,because there are more enzymes molecules available to catalyze the reaction.

At very high enzymes concentration the substrate concentration become limiting so the rate stops increasing and attain constant level.

Important point:

Normally enzymes present in cells in rather low concentration.

4-SUBSTRATE CONCENTRATION:

The graph between substrate concentration and rate of enzyme reaction shows that the substrate concentration has affect on rate of reaction.

If we increase the substrate concentration the rate of reaction increases but a moment reached at which adding more substrate has no effect on rate of reaction because at that time all enzymes are pre occupied by substrates and no free molecules of enzymes are available and as result reaction attain constant level.