Topic 4 chapter 5 part 3 enzymes - limiting factors

Topic 4: Chapter 5

Enzymes Enzymes – – Part 3Part 3

Limiting Limiting

FactorsFactors

What is a limiting factor?

Any factor that directly affects the rate of reaction at which a process occurs if its quantity is changed

The value of this factor has to be increased in order to increase the rate of the process

Factors affecting enzyme activity

1) Temperature2) pH3) Substrate

Concentration4) Enzyme

Concentration

Example 1 Point X

Example 1• Independent Variable: Substrate concentration

• LIMITING FACTOR IS Substrate concentration

From 0 to Point XFrom 0 to Point X

Description Explanation

As the [substrate] increases, the rate of reaction increases until Point X when rate of reaction reaches its maximum.

At any [substrate] before Point X, there are more enzyme molecules than substrate molecules

At Point X, all the enzyme active sites are occupied by substrate molecules


• LIMITING FACTOR IS Enzyme concentration

Beyond Point XBeyond Point X


Graph remains constant / becomes a plateau after Point X.

Maximum rate of reaction

After point X, the rate of reaction does not increase even when [substrate] increases.

This is because all the enzyme molecule’s active sites are being occupied at any one time. That is, all the enzyme molecules are saturated.

Amount of products formed per unit time remains constant

Example 2

0.4moldm-3 Enzyme

0.2moldm-3 Enzyme

Rat

e o

f R

eact

ion

Substrate Concentration / Arbitrary Units

(A)

(B)

X Y


From 0 to Point YFrom 0 to Point Y


Rate of reaction increases as [Substrate] increases for both Graphs A and B.

At any [Substrate] before Point Y, there are more enzymes than substrate molecules.

At Point X, all the enzyme active sites are occupied by substrate molecules

Rate of reaction of (B) is double that of (A)

There are double the number of enzyme molecules in (B). Double the frequency of collision between Enzyme and Substrate molecules in (B)

LIMITING FACTOR Substrate Concentration

Example 2• Independent Variable: Enzyme concentration

Beyond Point YBeyond Point Y

LIMITING FACTOR Enzyme Concentration


Graph remains constant / becomes a plateau after Point X.

Maximum rate of reaction

After point X, the rate of reaction does not increase even when [substrate] increases.

This is because all the enzyme molecule’s active sites are being occupied at any one time. That is, all the enzyme molecules are saturated.

Amount of products formed per unit time remains constant

Rate of reaction of (B) is double that of (A)

Double the number of enzyme molecules in (B). Double the number of E-S complex formed per unit time. Therefore, double the amount of products formed

Topic 4 chapter 5 part 3 enzymes - limiting factors

Technology

Transcript of Topic 4 chapter 5 part 3 enzymes - limiting factors