Enzyme

ENZYME

Characteristics of enzymes • Protein in nature & will be denatured at high temp. • Biological catalysts. Speed up reactions without being changed or used up. • They are reusable. • Action of enzymes are specific. • Work best at a certain range of pH and temperature.

Characteristics of enzymes enzyme Biological catalyst

pH

A+B

C

in e t o r P

Specificity

substrate substrate

active site

enzyme

Action of enzyme (Anabolic reaction) enzyme-substrate complex

substrate enzyme

enzyme-product complex

product

enzyme

Action of enzyme (catabolic reaction) enzyme-product complex

products enzyme

enzyme-substrate complex

substrate enzyme

Lock and key hypothesis product Substrate product

Enzyme

Lock and key hyphothesis S E P A T H S ’ N O D H C T A M

Factors affecting enzyme action Substrate concentration

Rate of reaction

Max. Rate

Substrate conc.

Factors affecting enzyme action Substrate concentration

Rate of reaction

Factors affecting enzyme action Temperature

0

10

20

30

40

50

Temperature （ OC ）

Factors affecting enzyme action Temperature • Each enzyme works best at a particular optimum temperature temperature - _____________________. • When temperature is lower than optimum temperature, activity of enzyme become lower At low temperature, enzymes ________. inactive become _____________. They become active again _________________ when the temperature is raised.

Factors affecting enzyme action Temperature • Above the optimum temperature, heat shape of enzymes and their changes the _______ active sites __________ decreases their _____________, activities. • When temperature is too high (above 60oC), denatured most enzymes are ____________, and lose they catalytic property permanently.

Rate of reaction

Factors affecting enzyme action pH

pH

Application of Enzymes

Washing Powder

SO Chi-shing Curriculum Officer (Biology) SCIENCE UNIT CURRICULUM DEVELOPMENT INSTITUTE EDUCATION DEPARTMENT